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Sample records for stretching region shows

  1. Stretching

    Science.gov (United States)

    ... after a workout. Stretching still can be a beneficial activity after you have sufficiently warmed up. The ... light aerobic activity and stretching. If you're running at a quick pace, you can slow down ...

  2. Regional Data Assimilation Using a Stretched-Grid Approach and Ensemble Calculations

    Science.gov (United States)

    Fox-Rabinovitz, M. S.; Takacs, L. L.; Govindaraju, R. C.; Atlas, Robert (Technical Monitor)

    2002-01-01

    The global variable resolution stretched grid (SG) version of the Goddard Earth Observing System (GEOS) Data Assimilation System (DAS) incorporating the GEOS SG-GCM (Fox-Rabinovitz 2000, Fox-Rabinovitz et al. 2001a,b), has been developed and tested as an efficient tool for producing regional analyses and diagnostics with enhanced mesoscale resolution. The major area of interest with enhanced regional resolution used in different SG-DAS experiments includes a rectangle over the U.S. with 50 or 60 km horizontal resolution. The analyses and diagnostics are produced for all mandatory levels from the surface to 0.2 hPa. The assimilated regional mesoscale products are consistent with global scale circulation characteristics due to using the SG-approach. Both the stretched grid and basic uniform grid DASs use the same amount of global grid-points and are compared in terms of regional product quality.

  3. A study of regional-scale aerosol assimilation using a Stretch-NICAM

    Science.gov (United States)

    Misawa, S.; Dai, T.; Schutgens, N.; Nakajima, T.

    2013-12-01

    Although aerosol is considered to be harmful to human health and it became a social issue, aerosol models and emission inventories include large uncertainties. In recent studies, data assimilation is applied to aerosol simulation to get more accurate aerosol field and emission inventory. Most of these studies, however, are carried out only on global scale, and there are only a few researches about regional scale aerosol assimilation. In this study, we have created and verified an aerosol assimilation system on regional scale, in hopes to reduce an error associated with the aerosol emission inventory. Our aerosol assimilation system has been developed using an atmospheric climate model, NICAM (Non-hydrostaric ICosahedral Atmospheric Model; Satoh et al., 2008) with a stretch grid system and coupled with an aerosol transport model, SPRINTARS (Takemura et al., 2000). Also, this assimilation system is based on local ensemble transform Kalman filter (LETKF). To validate this system, we used a simulated observational data by adding some artificial errors to the surface aerosol fields constructed by Stretch-NICAM-SPRINTARS. We also included a small perturbation in original emission inventory. This assimilation with modified observational data and emission inventory was performed in Kanto-plane region around Tokyo, Japan, and the result indicates the system reducing a relative error of aerosol concentration by 20%. Furthermore, we examined a sensitivity of the aerosol assimilation system by varying the number of total ensemble (5, 10 and 15 ensembles) and local patch (domain) size (radius of 50km, 100km and 200km), both of which are the tuning parameters in LETKF. The result of the assimilation with different ensemble number 5, 10 and 15 shows that the larger the number of ensemble is, the smaller the relative error become. This is consistent with ensemble Kalman filter theory and imply that this assimilation system works properly. Also we found that assimilation system

  4. Genomic Mapping of Human DNA provides Evidence of Difference in Stretch between AT and GC rich regions

    Science.gov (United States)

    Reifenberger, Jeffrey; Dorfman, Kevin; Cao, Han

    Human DNA is a not a polymer consisting of a uniform distribution of all 4 nucleic acids, but rather contains regions of high AT and high GC content. When confined, these regions could have different stretch due to the extra hydrogen bond present in the GC basepair. To measure this potential difference, human genomic DNA was nicked with NtBspQI, labeled with a cy3 like fluorophore at the nick site, stained with YOYO, loaded into a device containing an array of nanochannels, and imaged. Over 473,000 individual molecules of DNA, corresponding to roughly 30x coverage of a human genome, were collected and aligned to the human reference. Based on the known AT/GC content between aligned pairs of labels, the stretch was measured for regions of similar size but different AT/GC content. We found that regions of high GC content were consistently more stretched than regions of high AT content between pairs of labels varying in size between 2.5 kbp and 500 kbp. We measured that for every 1% increase in GC content there was roughly a 0.06% increase in stretch. While this effect is small, it is important to take into account differences in stretch between AT and GC rich regions to improve the sensitivity of detection of structural variations from genomic variations. NIH Grant: R01-HG006851.

  5. Multiplexed Microsphere Suspension-Array Assay for Urine Mitochondrial DNA Typing by C-Stretch Length in Hypervariable Regions.

    Science.gov (United States)

    Aoki, Kimiko; Tanaka, Hiroyuki; Kawahara, Takashi

    2018-07-01

    The standard method for personal identification and verification of urine samples in doping control is short tandem repeat (STR) analysis using nuclear DNA (nDNA). The DNA concentration of urine is very low and decreases under most conditions used for sample storage; therefore, the amount of DNA from cryopreserved urine samples may be insufficient for STR analysis. We aimed to establish a multiplexed assay for urine mitochondrial DNA typing containing only trace amounts of DNA, particularly for Japanese populations. A multiplexed suspension-array assay using oligo-tagged microspheres (Luminex MagPlex-TAG) was developed to measure C-stretch length in hypervariable region 1 (HV1) and 2 (HV2), five single nucleotide polymorphisms (SNPs), and one polymorphic indel. Based on these SNPs and the indel, the Japanese population can be classified into five major haplogroups (D4, B, M7a, A, D5). The assay was applied to DNA samples from urine cryopreserved for 1 - 1.5 years (n = 63) and fresh blood (n = 150). The assay with blood DNA enabled Japanese subjects to be categorized into 62 types, exhibiting a discriminatory power of 0.960. The detection limit for cryopreserved urine was 0.005 ng of nDNA. Profiling of blood and urine pairs revealed that 5 of 63 pairs showed different C-stretch patterns in HV1 or HV2. The assay described here yields valuable information in terms of the verification of urine sample sources employing only trace amounts of recovered DNA. However, blood cannot be used as a reference sample.

  6. a First-Principles Model of Fermi Resonance in the Alkyl CH Stretch Region: Application to Hydronaphthalenes, Indanes, and Cyclohexane

    Science.gov (United States)

    Sibert, Edwin; Kidwell, Nathanael; Zwier, Timothy S.

    2014-06-01

    The infrared (IR) spectroscopy of the alkyl CH stretch region (2750-3000 cm-1) of a series of bicyclic hydrocarbons and free radicals has been studied under supersonic expansion cooling in the gas phase, and compared with a theoretical model that describes the local mode stretch-bend Fermi resonance interactions. The double resonance method of fluorescence-dip infrared (FDIR) spectroscopy was used on the stable molecules 1,2-dihydronaphthalene, 1,4-dihydronaphthalene, tetralin, indene, and indane using the S_0-S_1 origin transition as a monitor of transitions. Resonant ion-dip infrared (RIDIR) spectra were recorded for the trihydronaphthyl (THN) and inden-2-yl methyl (I2M) radicals. The previously developed model Hamiltonian [J. Chem. Phys. 138 064308 (2013)] incorporates cubic stretch-bend coupling with parameters obtained from density functional theory methods. Full dimensional calculations are compared to reduced dimensional Hamiltonian results in which anharmonic CH streches and CH_2 scissor modes are Fermi coupled. Excellent agreement between theoretical results is found. Scale factors of select terms in the reduced dimensional Hamiltonian, obtained by fitting the theoretical Hamiltonian predictions to the experimental spectra, are found to be similar to previous work. The resulting Hamiltonian predicts successfully all the major spectral features considered in this study. A simplified model is introduced in which the CH_2 groups are decoupled. This model enables the assignment of many of the spectral features. The model results are extended to describe the CH stretch spectrum of the chair and twist-boat conformers of cyclohexane. The chair conformer is used to illustrate the shortcomings of the CH_2 coupling model.

  7. Periostin shows increased evolutionary plasticity in its alternatively spliced region

    Directory of Open Access Journals (Sweden)

    Hoersch Sebastian

    2010-01-01

    Full Text Available Abstract Background Periostin (POSTN is a secreted extracellular matrix protein of poorly defined function that has been related to bone and heart development as well as to cancer. In human and mouse, it is known to undergo alternative splicing in its C-terminal region, which is devoid of known protein domains. Differential expression of periostin, sometimes of specific splicing isoforms, is observed in a broad range of human cancers, including breast, pancreatic, and colon cancer. Here, we combine genomic and transcriptomic sequence data from vertebrate organisms to study the evolution of periostin and particularly of its C-terminal region. Results We found that the C-terminal part of periostin is markedly more variable among vertebrates than the rest of periostin in terms of exon count, length, and splicing pattern, which we interpret as a consequence of neofunctionalization after the split between periostin and its paralog transforming growth factor, beta-induced (TGFBI. We also defined periostin's sequential 13-amino acid repeat units - well conserved in teleost fish, but more obscure in higher vertebrates - whose secondary structure is predicted to be consecutive beta strands. We suggest that these beta strands may mediate binding interactions with other proteins through an extended beta-zipper in a manner similar to the way repeat units in bacterial cell wall proteins have been reported to bind human fibronectin. Conclusions Our results, obtained with the help of the increasingly large collection of complete vertebrate genomes, document the evolutionary plasticity of periostin's C-terminal region, and for the first time suggest a basis for its functional role.

  8. Boundary layer flow of an oldroyd-b fluid in the region of stagnation point over a stretching sheet

    International Nuclear Information System (INIS)

    Sajid, M.

    2012-01-01

    The mathematical modeling for the two-dimensional boundary layer flow of an Oldroyd-B fluid is presented. The developed equations are used to discuss the problem of two-dimensional flow in the region of a stagnation point over a stretching sheet. The obtained partial differential equations are reduced to an ordinary differential equation by a suitable transformation. The obtained equation is then solved using a finite difference method. The influence of the pertinent fluid parameters on the velocity is discussed through graphs. The behavior of f (0) is also investigated for the change in parameter values. Our main focus is to discuss the effects of relaxation and retardation time parameters on the velocity components in the x and y directions. In addition to it the skin friction coefficient is evaluated which is a measure of frictional drag at the surface illustrates that the boundary layer thickness decreases due to an increase in the relaxation time constant. The reason is that a higher relaxation time constant give rise to a slower recovery process and as a result the boundary layer thickness grows at a slower rate for a higher value of the relaxation time constant when compared with its lower value. (orig./A.B.)

  9. Stretch Marks

    Science.gov (United States)

    ... completely without the help of a dermatologist or plastic surgeon. These doctors may use one of many types of treatments — from actual surgery to techniques like microdermabrasion and laser treatment — to reduce the appearance of stretch marks. These techniques are ...

  10. The stretching amplitude and thermal regime of the lithosphere in the nonvolcanic passive margin of Antarctica in the Mawson Sea region

    Science.gov (United States)

    Galushkin, Yu. I.; Leitchenkov, G. L.; Guseva, Yu. B.; Dubinin, E. P.

    2018-01-01

    The burial history and thermal evolution of the lithosphere within the passive nonvolcanic Antarctic margin in the region of the Mawson Sea are numerically reconstructed for the margin areas along the seismic profile 5909 with the use of the GALO basin modeling system. The amplitudes of the lithosphere stretching at the different stages of continental rifting which took place from 160 to 90 Ma ago are calculated from the geophysical estimates of the thickness of the consolidated crust and the tectonic analysis of the variations in the thickness of the sedimentary cover and sea depths during the evolution of the basin. It is hypothesized that the formation of the recent sedimentary section sequence in the studied region of the Antarctic margin began 140 Ma ago on a basement that was thinned by a factor of 1.6 to 4.5 during the first episode of margin stretching (160-140 Ma) under a fairly high heat flux. The reconstruction of the thermal regime of the lithosphere has shown that the mantle rocks could occur within the temperature interval of serpentinization and simultaneously within the time interval of lithospheric stretching (-160 serpentinization could take place in these areas as in the other margin segments at the stage of presedimentation ultra slow basement stretching.

  11. Vitronectin Binds to a Specific Stretch within the Head Region of Yersinia Adhesin A and Thereby Modulates Yersinia enterocolitica Host Interaction.

    Science.gov (United States)

    Mühlenkamp, Melanie C; Hallström, Teresia; Autenrieth, Ingo B; Bohn, Erwin; Linke, Dirk; Rinker, Janina; Riesbeck, Kristian; Singh, Birendra; Leo, Jack C; Hammerschmidt, Sven; Zipfel, Peter F; Schütz, Monika S

    2017-01-01

    Complement resistance is an important virulence trait of Yersinia enterocolitica (Ye). The predominant virulence factor expressed by Ye is Yersinia adhesin A (YadA), which enables bacterial attachment to host cells and extracellular matrix and additionally allows the acquisition of soluble serum factors. The serum glycoprotein vitronectin (Vn) acts as an inhibitory regulator of the terminal complement complex by inhibiting the lytic pore formation. Here, we show YadA-mediated direct interaction of Ye with Vn and investigated the role of this Vn binding during mouse infection in vivo. Using different Yersinia strains, we identified a short stretch in the YadA head domain of Ye O:9 E40, similar to the 'uptake region' of Y. pseudotuberculosis YPIII YadA, as crucial for efficient Vn binding. Using recombinant fragments of Vn, we found the C-terminal part of Vn, including heparin-binding domain 3, to be responsible for binding to YadA. Moreover, we found that Vn bound to the bacterial surface is still functionally active and thus inhibits C5b-9 formation. In a mouse infection model, we demonstrate that Vn reduces complement-mediated killing of Ye O:9 E40 and, thus, improved bacterial survival. Taken together, these findings show that YadA-mediated Vn binding influences Ye pathogenesis. © 2016 S. Karger AG, Basel.

  12. The conserved 12-amino acid stretch in the inter-bromodomain region of BET family proteins functions as a nuclear localization signal.

    Science.gov (United States)

    Fukazawa, Hidesuke; Masumi, Atsuko

    2012-01-01

    The bromodomain and extraterminal (BET) family is a group of chromatin-binding proteins characterized by two bromodomains, an extraterminal (ET) domain, and several other conserved regions of unknown function. In humans, the BET family consists of four members, BRD2, BRD3, BRD4 and BRDT, that all normally localize to the nucleus. We identified a 12-amino acid stretch in the inter-bromodomain region that is perfectly conserved among the BET family members. We deleted these residues and expressed the mutant proteins in HEK293T cells to investigate the function of this motif. We found that the deletion of this motif alters the localization of BET proteins. Mutated BRD3 and BRD4 were excluded from the nucleus, and BRDT was found to be diffused throughout the nucleus and cytoplasm. Although the mutant BRD2 remained predominantly in the nucleus, a punctate distribution was also observed in the cytosol. It has been reported that a conserved motif between the second bromodomain and the ET domain serves as a nuclear localization signal for BRD2. Nevertheless, BET mutants lacking the reported nuclear localization signal motif but retaining the 12-amino acid stretch resided in the nucleus. Furthermore, these mutants were diffused throughout the cytoplasm when the 12 residues were removed. These results indicate that the conserved amino acid stretch in the inter-bromodomain region of the BET family functions as a nuclear localization signal.

  13. Stretch Sensor Device

    DEFF Research Database (Denmark)

    2013-01-01

    The invention relates to a method for determining stretch values and movement of body parts, e.g. a foot, by analysing stretch data from a stretch sensor. By analysing data from the stretch sensor it is possible to determine stretch samples which are associated with particular motion phases...

  14. Stretching Safely and Effectively

    Science.gov (United States)

    ... shown that stretching immediately before an event weakens hamstring strength. Instead of static stretching, try performing a " ... If you play soccer, for instance, stretch your hamstrings as you're more vulnerable to hamstring strains. ...

  15. Atomic Stretch: Optimally bounded real-time stretching and beyond

    DEFF Research Database (Denmark)

    Jensen, Rasmus Ramsbøl; Nielsen, Jannik Boll

    2016-01-01

    Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color-modification, co......Atomic Stretch is a plugin for your preferred Adobe video editing tool, allowing real-time smooth and optimally bounded retarget-ting from and to any aspect ratio. The plugin allows preserving of high interest pixels through a protected region, attention redirection through color...

  16. Crustal Stretching Style and Lower Crust Flow of the South China Sea Northern Margin

    Science.gov (United States)

    Bai, Y.; Dong, D.; Runlin, D.

    2017-12-01

    There is a controversy about crustal stretching style of the South China Sea (SCS) northern margin mainly due to considerable uncertainty of stretching factor estimation, for example, as much as 40% of upper crust extension (Walsh et al., 1991) would be lost by seismic profiles due to poor resolution. To discover and understand crustal stretching style and lower crustal flow on the whole, we map the Moho and Conrad geometries based on gravity inversion constrained by deep seismic profiles, then according to the assumption of upper and lower crust initial thickness, upper and lower crust stretching factors are estimated. According to the comparison between upper and lower crust stretching factors, the SCS northern margin could be segmented into three parts, (1) sediment basins where upper crust is stretched more than lower crust, (2) COT regions where lower crust is stretched more than upper crust, (3) other regions where the two layers have similar stretching factors. Stretching factor map shows that lower crust flow happened in both of COT and sediment basin regions where upper crust decouples with lower crust due to high temperature. Pressure contrast by sediment loading in basins and erosion in sediment-source regions will lead to lower crust flow away from sediment sink to source. Decoupled and fractured upper crust is stretched further by sediment loading and the following compensation would result in relatively thick lower crust than upper crust. In COT regions with thin sediment coverage, low-viscosity lower crust is easier to thin in extensional environment, also the lower crust tends to flow away induced by magma upwelling. Therefore, continental crust on the margin is not stretching in a constant way but varies with the tectonic setting changes. This work is supported by National Natural Science Foundation of China (Grant No. 41506055, 41476042) and Fundamental Research Funds for the Central Universities China (No.17CX02003A).

  17. Identification of a set of genes showing regionally enriched expression in the mouse brain

    Directory of Open Access Journals (Sweden)

    Marra Marco A

    2008-07-01

    Full Text Available Abstract Background The Pleiades Promoter Project aims to improve gene therapy by designing human mini-promoters ( Results We have utilized LongSAGE to identify regionally enriched transcripts in the adult mouse brain. As supplemental strategies, we also performed a meta-analysis of published literature and inspected the Allen Brain Atlas in situ hybridization data. From a set of approximately 30,000 mouse genes, 237 were identified as showing specific or enriched expression in 30 target regions of the mouse brain. GO term over-representation among these genes revealed co-involvement in various aspects of central nervous system development and physiology. Conclusion Using a multi-faceted expression validation approach, we have identified mouse genes whose human orthologs are good candidates for design of mini-promoters. These mouse genes represent molecular markers in several discrete brain regions/cell-types, which could potentially provide a mechanistic explanation of unique functions performed by each region. This set of markers may also serve as a resource for further studies of gene regulatory elements influencing brain expression.

  18. New investigation of the ν3 C-H stretching region of 12CH4 through the analysis of high temperature infrared emission spectra

    Science.gov (United States)

    Amyay, Badr; Gardez, Aline; Georges, Robert; Biennier, Ludovic; Vander Auwera, Jean; Richard, Cyril; Boudon, Vincent

    2018-04-01

    The ν3 C-H stretching region of methane was reinvestigated in this work using high temperature (620-1715 K) emission spectra recorded in Rennes at Doppler limited resolution. This work follows our recent global analysis of the Dyad system Δn = ±1 (1000-1500 cm-1), with n being the polyad number [B. Amyay et al., J. Chem. Phys. 144, 24312 (2016)]. Thanks to the high temperature, new assignments of vibration-rotation methane line positions have been achieved successfully in the Pentad system and some associated hot bands (Δn = ±2) observed in the spectral region 2600-3300 cm-1. In particular, rotational assignments in the cold band [Pentad-ground state (GS)] and in the first related hot band (Octad-Dyad) were extended up to J = 30 and 27, respectively. In addition, 1525 new transitions belonging to the Tetradecad-Pentad hot band system were assigned for the first time, up to J = 20. The effective global model used to deal with the new assignments was developed to the 6th order for the first three polyads (Monad, Dyad, and Pentad), and to the 5th order for both the Octad and the Tetradecad. 1306 effective parameters were fitted with a dimensionless standard deviation σ = 2.64. The root mean square deviations dRMS obtained are 4.18 × 10-3 cm-1 for the Pentad-GS cold band, 2.48 × 10-3 cm-1 for the Octad-Dyad, and 1.43 × 10-3 cm-1 for the Tetradecad-Pentad hot bands.

  19. Knotting in stretched polygons

    International Nuclear Information System (INIS)

    Rensburg, E J Janse van; Orlandini, E; Tesi, M C; Whittington, S G

    2008-01-01

    The knotting in a lattice polygon model of ring polymers is examined when a stretching force is applied to the polygon. By examining the incidence of cut-planes in the polygon, we prove a pattern theorem in the stretching regime for large applied forces. This theorem can be used to examine the incidence of entanglements such as knotting and writhing. In particular, we prove that for arbitrarily large positive, but finite, values of the stretching force, the probability that a stretched polygon is knotted approaches 1 as the length of the polygon increases. In the case of writhing, we prove that for stretched polygons of length n, and for every function f(n)=o(√n), the probability that the absolute value of the mean writhe is less than f(n) approaches 0 as n → ∞, for sufficiently large values of the applied stretching force

  20. The Relation Between Stretching Typology and Stretching Duration: The Effects on Range of Motion.

    Science.gov (United States)

    Thomas, Ewan; Bianco, Antonino; Paoli, Antonio; Palma, Antonio

    2018-04-01

    Different stretching strategies and protocols are widely used to improve flexibility or maintain health, acting on the muscle tendon-unit, in order to improve the range of motion (ROM) of the joints. This review aims to evaluate the current body of literature in order to understand the relation between stretching typology and ROM, and secondly to evaluate if a relation exists between stretching volume (either as a single training session, weekly training and weekly frequency) and ROM, after long-term stretching. Twenty-three articles were considered eligible and included in the quantitative synthesis. All stretching typologies showed ROM improvements over a long-term period, however the static protocols showed significant gains (p<0.05) when compared to the ballistic or PNF protocols. Time spent stretching per week seems fundamental to elicit range of movement improvements when stretches are applied for at least or more than 5 min, whereas the time spent stretching within a single session does not seem to have significant effects for ROM gains. Weekly frequency is positively associated to ROM. Evaluated data indicates that performing stretching at least 5 days a week for at least 5 min per week using static stretching may be beneficial to promote ROM improvements. © Georg Thieme Verlag KG Stuttgart · New York.

  1. Idiopathic cases of male infertility from a region in India show low ...

    Indian Academy of Sciences (India)

    Unknown

    with poor morphology and motility) – were examined. An institutional ethical committee had approved analysis of genetic disorders in ..... Havighurst T and Grosch J 1999 Defining regions of the Y- chromosome responsible for male infertility and identi- fication of a fourth AZF region (AZFd) by Y-chromosome microdeletion ...

  2. Regional Brain Activation during Meditation Shows Time and Practice Effects: An Exploratory FMRI Study

    Directory of Open Access Journals (Sweden)

    E. Baron Short

    2010-01-01

    Full Text Available Meditation involves attentional regulation and may lead to increased activity in brain regions associated with attention such as dorsal lateral prefrontal cortex (DLPFC and anterior cingulate cortex (ACC. Using functional magnetic resonance imaging, we examined whether DLPFC and ACC were activated during meditation. Subjects who meditate were recruited and scanned on a 3.0 Tesla scanner. Subjects meditated for four sessions of 12 min and performed four sessions of a 6 min control task. Individual and group t-maps were generated of overall meditation response versus control response and late meditation response versus early meditation response for each subject and time courses were plotted. For the overall group (n = 13, and using an overall brain analysis, there were no statistically significant regional activations of interest using conservative thresholds. A region of interest analysis of the entire group time courses of DLPFC and ACC were statistically more active throughout meditation in comparison to the control task. Moreover, dividing the cohort into short (n = 8 and long-term (n = 5 practitioners (>10 years revealed that the time courses of long-term practitioners had significantly more consistent and sustained activation in the DLPFC and the ACC during meditation versus control in comparison to short-term practitioners. The regional brain activations in the more practised subjects may correlate with better sustained attention and attentional error monitoring. In summary, brain regions associated with attention vary over the time of a meditation session and may differ between long- and short-term meditation practitioners.

  3. Redeployment of germ layers related TFs shows regionalized expression during two non-embryonic developments.

    Science.gov (United States)

    Ricci, Lorenzo; Cabrera, Fabien; Lotito, Sonia; Tiozzo, Stefano

    2016-08-01

    In all non-vertebrate metazoan phyla, species that evolved non-embryonic developmental pathways as means of propagation or regeneration can be found. In this context, new bodies arise through asexual reproduction processes (such as budding) or whole body regeneration, that lack the familiar temporal and spatial cues classically associated with embryogenesis, like maternal determinants, or gastrulation. The molecular mechanisms underlying those non-embryonic developments (i.e., regeneration and asexual reproduction), and their relationship to those deployed during embryogenesis are poorly understood. We have addressed this question in the colonial ascidian Botryllus schlosseri, which undergoes an asexual reproductive process via palleal budding (PB), as well as a whole body regeneration by vascular budding (VB). We identified early regenerative structures during VB and then followed the fate of differentiating tissues during both non-embryonic developments (PB and VB) by monitoring the expression of genes known to play key functions in germ layer specification with well conserved expression patterns in solitary ascidian embryogenesis. The expression patterns of FoxA1, GATAa, GATAb, Otx, Bra, Gsc and Tbx2/3 were analysed during both PB and VB. We found that the majority of these transcription factors were expressed during both non-embryonic developmental processes, revealing a regionalization of the palleal and vascular buds. Knockdown of GATAa by siRNA in palleal buds confirmed that preventing the correct development of one of these regions blocks further tissue specification. Our results indicate that during both normal and injury-induced budding, a similar alternative developmental program operates via early commitment of epithelial regions. Copyright © 2016. Published by Elsevier Inc.

  4. BSDB: the Biomolecule Stretching Database

    Science.gov (United States)

    Cieplak, Marek; Sikora, Mateusz; Sulkowska, Joanna I.; Witkowski, Bartlomiej

    2011-03-01

    Despite more than a decade of experiments on single biomolecule manipulation, mechanical properties of only several scores of proteins have been measured. A characteristic scale of the force of resistance to stretching, Fmax , has been found to range between ~ 10 and 480 pN. The Biomolecule Stretching Data Base (BSDB) described here provides information about expected values of Fmax for, currently, 17 134 proteins. The values and other characteristics of the unfolding proces, including the nature of identified mechanical clamps, are available at www://info.ifpan.edu.pl/BSDB/. They have been obtained through simulations within a structure-based model which correlates satisfactorily with the available experimental data on stretching. BSDB also lists experimental data and results of the existing all-atom simulations. The database offers a Protein-Data-Bank-wide guide to mechano-stability of proteins. Its description is provided by a forthcoming Nucleic Acids Research paper. Supported by EC FUNMOL project FP7-NMP-2007-SMALL-1, and European Regional Development Fund: Innovative Economy (POIG.01.01.02-00-008/08).

  5. Idiopathic cases of male infertility from a region in India show low ...

    Indian Academy of Sciences (India)

    Unknown

    9 (azoospermia – 8 and oligoasthenospermia – 1) showed partial deletion of AZF ... such as diabetes, obesity, varicocele, cystic fibrosis or .... ing pregnancy was maintained for each patient. .... rized as Sertoli cell only syndrome type 1 (SCO I).

  6. Stretch due to Penile Prosthesis Reservoir Migration

    Directory of Open Access Journals (Sweden)

    E. Baten

    2016-03-01

    Full Text Available A 43-year old patient presented to the emergency department with stretch, due to impossible deflation of the penile prosthesis, 4 years after successful implant. A CT-scan showed migration of the reservoir to the left rectus abdominis muscle. Refilling of the reservoir was inhibited by muscular compression, causing stretch. Removal and replacement of the reservoir was performed, after which the prosthesis was well-functioning again. Migration of the penile prosthesis reservoir is extremely rare but can cause several complications, such as stretch.

  7. Stretched alignment due to pairing correlation between the normal and abnormal parity orbits for the γ-soft nuclei in the light rare-earth region

    International Nuclear Information System (INIS)

    Ding, H.; Wu, L.

    1996-01-01

    For the γ-soft rotational motion, a two-parameter model is constructed considering the pair correlation between the normal and abnormal parity states based on the fermion dynamical symmetry model. The numerical calculation of this model shows that the data of ground bands of ten typical γ-soft rotational nuclei in the light rare-earth region are fitted in a very high quality. copyright 1996 The American Physical Society

  8. Foam topology. Bending versus stretching dominated architectures

    International Nuclear Information System (INIS)

    Deshpande, V.; Ashby, M.; Fleck, N.

    2000-01-01

    Cellular solids can deform by either the bending or stretching of the cell walls. While most cellular solids are bending-dominated, those that are stretching-dominated are much more weight-efficient for structural applications. In this study we have investigated the topological criteria that dictate the deformation mechanism of a cellular solid by analysing the rigidity (or otherwise) of pin-jointed frameworks comprising inextensional struts. We show that the minimum node connectivity for a special class of lattice structured materials to be stretching-dominated is 6 for 2D foams and 12 for 3D foams. Similarly, sandwich plates comprising of truss cores faced with planar trusses require a minimum node connectivity of 9 to undergo stretching-dominated deformation for all loading states. (author)

  9. Buckling and stretching of thin viscous sheets

    Science.gov (United States)

    O'Kiely, Doireann; Breward, Chris; Griffiths, Ian; Howell, Peter; Lange, Ulrich

    2016-11-01

    Thin glass sheets are used in smartphone, battery and semiconductor technology, and may be manufactured by producing a relatively thick glass slab and subsequently redrawing it to a required thickness. The resulting sheets commonly possess undesired centerline ripples and thick edges. We present a mathematical model in which a viscous sheet undergoes redraw in the direction of gravity, and show that, in a sufficiently strong gravitational field, buckling is driven by compression in a region near the bottom of the sheet, and limited by viscous resistance to stretching of the sheet. We use asymptotic analysis in the thin-sheet, low-Reynolds-number limit to determine the centerline profile and growth rate of such a viscous sheet.

  10. Stretching & Flexibility: An Interactive Encyclopedia of Stretching. [CD-ROM].

    Science.gov (United States)

    2002

    This CD-ROM offers 140 different stretches in full-motion video sequences. It focuses on the proper techniques for overall physical fitness, injury prevention and rehabilitation, and 23 different sports (e.g., golf, running, soccer, skiing, climbing, football, and baseball). Topics include stretching for sports; stretching awareness and education…

  11. Stretching the Border

    DEFF Research Database (Denmark)

    Horstmann, Alexander

    2014-01-01

    In this paper, I hope to add a complementary perspective to James Scott’s recent work on avoidance strategies of subaltern mountain people by focusing on what I call the refugee public. The educated Karen elite uses the space of exile in the Thai borderland to reconstitute resources and to re-ent......-based organizations succeed to stretch the border by establishing a firm presence that is supported by the international humanitarian economy in the refugee camps in Northwestern Thailand....

  12. A method to determine the mammographic regions that show early changes due to the development of breast cancer

    Science.gov (United States)

    Karemore, Gopal; Nielsen, Mads; Karssemeijer, Nico; Brandt, Sami S.

    2014-11-01

    It is well understood nowadays that changes in the mammographic parenchymal pattern are an indicator of a risk of breast cancer and we have developed a statistical method that estimates the mammogram regions where the parenchymal changes, due to breast cancer, occur. This region of interest is computed from a score map by utilising the anatomical breast coordinate system developed in our previous work. The method also makes an automatic scale selection to avoid overfitting while the region estimates are computed by a nested cross-validation scheme. In this way, it is possible to recover those mammogram regions that show a significant difference in classification scores between the cancer and the control group. Our experiments suggested that the most significant mammogram region is the region behind the nipple and that can be justified by previous findings from other research groups. This result was conducted on the basis of the cross-validation experiments on independent training, validation and testing sets from the case-control study of 490 women, of which 245 women were diagnosed with breast cancer within a period of 2-4 years after the baseline mammograms. We additionally generalised the estimated region to another, mini-MIAS study and showed that the transferred region estimate gives at least a similar classification result when compared to the case where the whole breast region is used. In all, by following our method, one most likely improves both preclinical and follow-up breast cancer screening, but a larger study population will be required to test this hypothesis.

  13. A method to determine the mammographic regions that show early changes due to the development of breast cancer

    International Nuclear Information System (INIS)

    Karemore, Gopal; Nielsen, Mads; Brandt, Sami S; Karssemeijer, Nico

    2014-01-01

    It is well understood nowadays that changes in the mammographic parenchymal pattern are an indicator of a risk of breast cancer and we have developed a statistical method that estimates the mammogram regions where the parenchymal changes, due to breast cancer, occur. This region of interest is computed from a score map by utilising the anatomical breast coordinate system developed in our previous work. The method also makes an automatic scale selection to avoid overfitting while the region estimates are computed by a nested cross-validation scheme. In this way, it is possible to recover those mammogram regions that show a significant difference in classification scores between the cancer and the control group. Our experiments suggested that the most significant mammogram region is the region behind the nipple and that can be justified by previous findings from other research groups. This result was conducted on the basis of the cross-validation experiments on independent training, validation and testing sets from the case-control study of 490 women, of which 245 women were diagnosed with breast cancer within a period of 2–4 years after the baseline mammograms. We additionally generalised the estimated region to another, mini-MIAS study and showed that the transferred region estimate gives at least a similar classification result when compared to the case where the whole breast region is used. In all, by following our method, one most likely improves both preclinical and follow-up breast cancer screening, but a larger study population will be required to test this hypothesis. (paper)

  14. Stretching of material lines in pseudo-turbulence induced by small rising bubbles

    International Nuclear Information System (INIS)

    Tanaka, M; Tsujimura, Y; Kanatani, H

    2011-01-01

    Direct numerical simulations have been conducted for the stretching of material lines in pseudo-turbulence induced by small rising bubbles in order to understand the mixing characteristics of bubbly flows. Contaminated bubbles are considered and are treated as light solid particles. An immersed boundary method has been used for evaluating the coupling force between the bubbles and the surrounding fluid flows. Numerical results show that the total length of material lines increases exponentially in time as a result of stretching and folding due to the rising bubbles. The material lines tend to accumulate in the wake regions of the bubbles, and they are strongly stretched in the vertical direction there. It is also found that the stretching rate of material lines increases with the mean void fraction when it is normalized by the magnitude of the rate-of-strain tensor of liquid flow in pseudo-turbulence. In the case of high void fractions, material lines tend to align with the direction of maximum stretching, and are effectively stretched.

  15. Stretching of material lines in pseudo-turbulence induced by small rising bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, M; Tsujimura, Y; Kanatani, H, E-mail: mtanaka@kit.ac.jp [Department of Mechanical and System Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan)

    2011-12-22

    Direct numerical simulations have been conducted for the stretching of material lines in pseudo-turbulence induced by small rising bubbles in order to understand the mixing characteristics of bubbly flows. Contaminated bubbles are considered and are treated as light solid particles. An immersed boundary method has been used for evaluating the coupling force between the bubbles and the surrounding fluid flows. Numerical results show that the total length of material lines increases exponentially in time as a result of stretching and folding due to the rising bubbles. The material lines tend to accumulate in the wake regions of the bubbles, and they are strongly stretched in the vertical direction there. It is also found that the stretching rate of material lines increases with the mean void fraction when it is normalized by the magnitude of the rate-of-strain tensor of liquid flow in pseudo-turbulence. In the case of high void fractions, material lines tend to align with the direction of maximum stretching, and are effectively stretched.

  16. Stretched polygons in a lattice tube

    Energy Technology Data Exchange (ETDEWEB)

    Atapour, M [Department of Mathematics and Statistics, York University, Toronto, ON M3J 1P3 (Canada); Soteros, C E [Department of Mathematics and Statistics, University of Saskatchewan, Saskatoon, SK S7N 5E6 (Canada); Whittington, S G [Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6 (Canada)], E-mail: atapour@mathstat.yorku.ca, E-mail: soteros@math.usask.ca, E-mail: swhittin@chem.utoronto.ca

    2009-08-14

    We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n {yields} {infinity}. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n {yields} {infinity}. Thus as n {yields} {infinity} when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

  17. Stretched polygons in a lattice tube

    International Nuclear Information System (INIS)

    Atapour, M; Soteros, C E; Whittington, S G

    2009-01-01

    We examine the topological entanglements of polygons confined to a lattice tube and under the influence of an external tensile force f. The existence of the limiting free energy for these so-called stretched polygons is proved and then, using transfer matrix arguments, a pattern theorem for stretched polygons is proved. Note that the tube constraint allows us to prove a pattern theorem for any arbitrary value of f, while without the tube constraint it has so far only been proved for large values of f. The stretched polygon pattern theorem is used first to show that the average span per edge of a randomly chosen n-edge stretched polygon approaches a positive value, non-decreasing in f, as n → ∞. We then show that the knotting probability of an n-edge stretched polygon confined to a tube goes to one exponentially as n → ∞. Thus as n → ∞ when polygons are influenced by a force f, no matter its strength or direction, topological entanglements, as defined by knotting, occur with high probability. (fast track communication)

  18. Static versus dynamic stretching: Chronic and acute effects on Agility performance in male athletes

    Directory of Open Access Journals (Sweden)

    Iman Taleb-Beydokhti

    2015-04-01

    Full Text Available The purpose of this study was to examine the acute and chronic effects of static & dynamic stretching protocols on agility performance in amateur handball players. Twelve male amateur handball players (age: 19.66 ± 4.02 years old, weight: 67.12 ± 8.73 kg, height: 178.29 ± 7.81 cm participated in this study. The athletes were randomly allocated into two groups: static stretching or dynamic stretching. All of them underwent an initial evaluation and were submitted to the first intervention. They were evaluated once again and at the end of 12 training sessions. The results analyzed using ANOVA showed that there was a significant decrease in agility time after dynamic stretching against no stretching in the acute phase; but, there were no significant differences between dynamic stretching and no stretching in the chronic phase. In addition, there was no a significant difference between no stretching and static stretching in the acute phase; while, There was a significant decrease in agility time after no stretching against static stretching in the chronic phase. It was concluded that acute dynamic stretching as part of a warm-up may decrease agility time performance, whereas static stretching seems to increase agility time performance. Consequently, the acute and chronic static stretching should not be performed prior to an explosive athletic performance. Keywords: Handball, Agility, Dynamic stretching, Static stretching

  19. Correlation between structure and conductivity in stretched Nafion

    Science.gov (United States)

    Allahyarov, Elshad; Taylor, Philip

    2008-03-01

    We have used coarse-grained simulation methods to investigate the effect of stretching-induced structure orientation on the proton conductivity of Nafion-like polyelectrolyte membranes. Recent experimental data on the morphology of ionomers describe Nafion as an aggregation of polymeric backbone chains forming elongated objects embedded in a continuous ionic medium. Uniaxial stretching of a recast Nafion film causes a preferential orientation of these objects in the direction of stretching. Our simulations of humid Nafion show that this has a strong effect on the proton conductivity, which is enhanced along the stretching direction, while the conductivity perpendicular to the stretched polymer backbone is strongly reduced. Stretching also causes the perfluorinated side chains to orient perpendicular to the stretching axis. The sulphonate multiplets shrink in diameter as the stretching is increased and show a spatially periodic ordering in their distribution. This in turn affects the distribution of contained water at low water contents. The water forms a continuous network with narrow bridges between small water clusters absorbed in head-group multiplets. We find the morphological changes in the stretched Nafion to be retained upon removal of the uniaxial stress.

  20. Contact angles on stretched solids

    Science.gov (United States)

    Mensink, Liz; Snoeijer, Jacco

    2017-11-01

    The surface energy of solid interfaces plays a central role in wetting, as they dictate the liquid contact angle. Yet, it has been challenging to measure the solid surface energies independently, without making use of Young's law. Here we present Molecular Dynamics (MD) simulations by which we measure the surface properties for all interfaces, including the solids. We observe change in contact angles upon stretching the solid substrates, showing that the surface energy is actually strain dependent. This is clear evidence of the so-called Shuttleworth effect, making it necessary to distinguish surface energy from surface tension. We discuss how this effect gives rise to a new class of elasto-capillary phenomena. ERC Consolidator Grant No. 616918.

  1. Optical stretching on chip with acoustophoretic prefocusing

    DEFF Research Database (Denmark)

    Khoury Arvelo, Maria; Laub Busk, L.; Bruus, Henrik

    2012-01-01

    in the microchannel. Trapping and manipulation is demonstrated for dielectric beads. In addition, we show trapping, manipulation and stretching of red blood cells and vesicles, whereby we extract the elastic properties of these objects. Our design points towards the construction of a low-cost, high-throughput lab...

  2. Passive Stretch Versus Active Stretch on Intervertebral Movement in Non - Specific Neck Pain

    International Nuclear Information System (INIS)

    Abd El - Aziz, A.H.; Amin, D.I.; Moustafa, I.

    2016-01-01

    Neck pain is one of the most common and painful musculoskeletal conditions. Point prevalence ranges from 6% to 22% and up to 38% of the elderly population, while lifetime prevalence ranges from 14,2% to 71%. Up till now no randomized study showed the effect between controversy of active and passive stretch on intervertebral movement. The purpose: the current study was to investigate the effect of the passive and active stretch on intervertebral movement in non - specific neck pain. Material and methods: Forty five subjects from both sexes with age range between 18 and 30 years and assigned in three groups, group I (15) received active stretch, ultrasound and TENS. Group II (15) received passive stretch, ultrasound and TENS. Group III (15) received ultrasound and TENS. The radiological assessment was used to measure rotational and translational movement of intervertebral movement before and after treatment. Results: MANOVA test was used for radiological assessment before and after treatment there was significant increase in intervertebral movement in group I as p value =0.0001. Conclusion: active stretch had a effect in increasing the intervertebral movement compared to the passive stretch

  3. EFFECTIVENESS OF PNF STRETCHING VERSUS STATIC STRETCHING ON PAIN AND HAMSTRING FLEXIBILITY FOLLOWING MOIST HEAT IN INDIVIDUALS WITH KNEE OSTEOARTHRITIS

    Directory of Open Access Journals (Sweden)

    Meena .V

    2016-10-01

    Full Text Available Background: Osteoarthritis (OA is a degenerative joint disease and one of the major public health problem that causesfunctional impairment and reduced quality of life. To compare the effectiveness of PNF Hold relax stretching versus Static stretching on pain and flexibility of hamstring following moist heat in individuals with knee osteoarthritis. Hamstring tightness is the major problem in knee osteoarthritis individuals. Therefore the need of study is comparing the effectiveness of PNF Hold relax stretching versus static stretching on pain and flexibility of hamstrings following moist heat in knee osteoarthritis participants. Determining the effects of PNF Hold relax stretching versus Static stretching along with moist heat on pain and hamstring flexibility by VAS and Active knee extension range of motion in knee osteoarthritis individuals. Methods: 30 subjects with symptoms of knee osteoarthritis were randomly distributed into 2 groups 15 in each group. PNF Hold relax stretching along with moist heat is compared to Static stretching along with moist heat. Pain was measured by Visual Analogue Scale (VAS and hamstring flexibility by Active knee Extension Range of Motion (AKEROM by universal goniometer. Measurements are taken pre and post intervention. Results: The results indicated PNF Hold relax stretching along with moist heat showed a statistically significant improvement in pain (p<0.05 and improvement in hamstring flexibility (p<0.05 when compared to Static stretching along with moist heat. Conclusion: Subjects with PNF Hold relax stretching along with moist heat showed significant improvement in pain reduction and improving hamstring flexibility than Static stretching along with moist heat.

  4. Transport, mixing and stretching in a chaotic Stokes flow: The two-roll mill

    International Nuclear Information System (INIS)

    Kaper, T.J.; Wiggins, S.

    1989-01-01

    We present the outline and preliminary results of an analytical and numerical study of transport, mixing, and stretching in a chaotic Stokes' flow in a two-roll mill apparatus. We use the theory of dynamical systems to describe the rich behavior and structure exhibited by these flows. The main features are the homoclinic tangle which functions as the backbone of the chaotic mixing region, the Smale horseshoe, and the island chains. We then use our detailed knowledge of these structures to develop a theory of transport and stretching of fluid in the chaotic regime. In particular, we show how a specific set of tools for adiabatic chaos- the adiabatic Melnikov function lobe area and flux computations and the adiabatic switching method is ideally suited to develop this theory of transport, mixing and stretching in time-dependent two-dimensional Stokes' flows. 19 refs., 8 figs

  5. EFFICACY OF MODIFIED PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING WITH CRYOTHERAPY OVER MANUAL PASSIVE STRETCHING WITH CRYOTHERAPY ON HAMSTRING FLEXIBILITY

    Directory of Open Access Journals (Sweden)

    Shamik Bhattacharjee

    2016-04-01

    Full Text Available Background: Healthy individuals, to ease and accomplish their activities of daily living they need flexible body without any tightness in the muscles, particularly those used for a definite function. Cooling soft tissues in a lengthened position after stretching has been shown to promote more lasting increases in soft tissue length and minimize post stretch muscle soreness. There are less documented studies which compared modified proprioceptive neuromuscular facilitation (PNF stretch over passive manual stretch with cold application commonly after the interventions. Methods: Thirty high school going healthy students were divided into two groups- Group I received Passive Manual stretching (n=15 and Group II received modified PNF stretching (n=15 and both groups received cold application after the interventions for 10 minutes commonly for 5 days. ROM was taken on day 1, day 5 and day 7. Results: After day 7, Group II with Modified PNF stretching along with cold application showed a significant increase in range of motion tested with active knee extension test (AKET. Conclusion: Modified PNF stretching is considered to be the effective intervention in increasing and maintaining ROM in AKET over passive manual stretching with cold applications commonly after the interventions.

  6. Stretch-minimising stream surfaces

    KAUST Repository

    Barton, Michael; Kosinka, Jin; Calo, Victor M.

    2015-01-01

    We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these 'stretch-free' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

  7. Stretch-minimising stream surfaces

    KAUST Repository

    Barton, Michael

    2015-05-01

    We study the problem of finding stretch-minimising stream surfaces in a divergence-free vector field. These surfaces are generated by motions of seed curves that propagate through the field in a stretch minimising manner, i.e., they move without stretching or shrinking, preserving the length of their arbitrary arc. In general fields, such curves may not exist. How-ever, the divergence-free constraint gives rise to these \\'stretch-free\\' curves that are locally arc-length preserving when infinitesimally propagated. Several families of stretch-free curves are identified and used as initial guesses for stream surface generation. These surfaces are subsequently globally optimised to obtain the best stretch-minimising stream surfaces in a given divergence-free vector field. Our algorithm was tested on benchmark datasets, proving its applicability to incompressible fluid flow simulations, where our stretch-minimising stream surfaces realistically reflect the flow of a flexible univariate object. © 2015 Elsevier Inc. All rights reserved.

  8. Global morphological analysis of marine viruses shows minimal regional variation and dominance of non-tailed viruses.

    Science.gov (United States)

    Brum, Jennifer R; Schenck, Ryan O; Sullivan, Matthew B

    2013-09-01

    Viruses influence oceanic ecosystems by causing mortality of microorganisms, altering nutrient and organic matter flux via lysis and auxiliary metabolic gene expression and changing the trajectory of microbial evolution through horizontal gene transfer. Limited host range and differing genetic potential of individual virus types mean that investigations into the types of viruses that exist in the ocean and their spatial distribution throughout the world's oceans are critical to understanding the global impacts of marine viruses. Here we evaluate viral morphological characteristics (morphotype, capsid diameter and tail length) using a quantitative transmission electron microscopy (qTEM) method across six of the world's oceans and seas sampled through the Tara Oceans Expedition. Extensive experimental validation of the qTEM method shows that neither sample preservation nor preparation significantly alters natural viral morphological characteristics. The global sampling analysis demonstrated that morphological characteristics did not vary consistently with depth (surface versus deep chlorophyll maximum waters) or oceanic region. Instead, temperature, salinity and oxygen concentration, but not chlorophyll a concentration, were more explanatory in evaluating differences in viral assemblage morphological characteristics. Surprisingly, given that the majority of cultivated bacterial viruses are tailed, non-tailed viruses appear to numerically dominate the upper oceans as they comprised 51-92% of the viral particles observed. Together, these results document global marine viral morphological characteristics, show that their minimal variability is more explained by environmental conditions than geography and suggest that non-tailed viruses might represent the most ecologically important targets for future research.

  9. Land surveys show regional variability of historical fire regimes and dry forest structure of the western United States.

    Science.gov (United States)

    Baker, William L; Williams, Mark A

    2018-03-01

    An understanding of how historical fire and structure in dry forests (ponderosa pine, dry mixed conifer) varied across the western United States remains incomplete. Yet, fire strongly affects ecosystem services, and forest restoration programs are underway. We used General Land Office survey reconstructions from the late 1800s across 11 landscapes covering ~1.9 million ha in four states to analyze spatial variation in fire regimes and forest structure. We first synthesized the state of validation of our methods using 20 modern validations, 53 historical cross-validations, and corroborating evidence. These show our method creates accurate reconstructions with low errors. One independent modern test reported high error, but did not replicate our method and made many calculation errors. Using reconstructed parameters of historical fire regimes and forest structure from our validated methods, forests were found to be non-uniform across the 11 landscapes, but grouped together in three geographical areas. Each had a mixture of fire severities, but dominated by low-severity fire and low median tree density in Arizona, mixed-severity fire and intermediate to high median tree density in Oregon-California, and high-severity fire and intermediate median tree density in Colorado. Programs to restore fire and forest structure could benefit from regional frameworks, rather than one size fits all. © 2018 by the Ecological Society of America.

  10. Optimal stretching in the reacting wake of a bluff body.

    Science.gov (United States)

    Wang, Jinge; Tithof, Jeffrey; Nevins, Thomas D; Colón, Rony O; Kelley, Douglas H

    2017-12-01

    We experimentally study spreading of the Belousov-Zhabotinsky reaction behind a bluff body in a laminar flow. Locations of reacted regions (i.e., regions with high product concentration) correlate with a moderate range of Lagrangian stretching and that range is close to the range of optimal stretching previously observed in topologically different flows [T. D. Nevins and D. H. Kelley, Phys. Rev. Lett. 117, 164502 (2016)]. The previous work found optimal stretching in a closed, vortex dominated flow, but this article uses an open flow and only a small area of appreciable vorticity. We hypothesize that optimal stretching is common in advection-reaction-diffusion systems with an excitation threshold, including excitable and bistable systems, and that the optimal range depends on reaction chemistry and not on flow shape or characteristic speed. Our results may also give insight into plankton blooms behind islands in ocean currents.

  11. Characterization of mechanical behavior of a porcine pulmonary artery strip using a randomized uniaxial stretch and stretch-rate protocol

    Directory of Open Access Journals (Sweden)

    Criscione John C

    2008-01-01

    significantly with increasing stretch to a nadir of 3.6% for a stretch of 1.7. The inelastic deviation then increased with increasing stretch at the same point in the stress-strain curve where stiffness began to increase strikingly. MLRA showed that T is a major inelastic parameter at low deformation. For moderate and high deformations, Ht2 and Ht1 were dominant. Discussion A randomized uniaxial testing protocol was applied to a strip of porcine pulmonary artery to characterize the elasticity and inelasticity of a soft tissue. We were successful in determining the elastic response and the factors that gave rise to the inelastic deviation. This investigation seeks methods to better define, phenomenologically, the elastic and inelastic behavior of soft tissues.

  12. Ductile Glass of Polyrotaxane Toughened by Stretch-Induced Intramolecular Phase Separation.

    Science.gov (United States)

    Kato, Kazuaki; Nemoto, Kaito; Mayumi, Koichi; Yokoyama, Hideaki; Ito, Kohzo

    2017-09-27

    A new class of ductile glasses is created from a thermoplastic polyrotaxane. The hard glass, which has a Young's modulus of 1 GPa, shows crazing, necking, and strain hardening with a total elongation of 330%. Stress concentration is prevented through a unique stretch-induced intramolecular phase separation of the cyclic components and the exposed backbone. In situ synchrotron X-ray scattering studies indicate that the backbone polymer chains slip through the cyclic components in the regions where the stress is concentrated.

  13. The effectiveness of manual stretching in the treatment of plantar heel pain: a systematic review

    Directory of Open Access Journals (Sweden)

    Parish Ben

    2011-06-01

    Full Text Available Abstract Background Plantar heel pain is a commonly occurring foot complaint. Stretching is frequently utilised as a treatment, yet a systematic review focusing only on its effectiveness has not been published. This review aimed to assess the effectiveness of stretching on pain and function in people with plantar heel pain. Methods Medline, EMBASE, CINAHL, AMED, and The Cochrane Library were searched from inception to July 2010. Studies fulfilling the inclusion criteria were independently assessed, and their quality evaluated using the modified PEDro scale. Results Six studies including 365 symptomatic participants were included. Two compared stretching with a control, one study compared stretching to an alternative intervention, one study compared stretching to both alternative and control interventions, and two compared different stretching techniques and durations. Quality rating on the modified Pedro scale varied from two to eight out of a maximum of ten points. The methodologies and interventions varied significantly between studies, making meta-analysis inappropriate. Most participants improved over the course of the studies, but when stretching was compared to alternative or control interventions, the changes only reached statistical significance in one study that used a combination of calf muscle stretches and plantar fascia stretches in their stretching programme. Another study comparing different stretching techniques, showed a statistically significant reduction in some aspects of pain in favour of plantar fascia stretching over calf stretches in the short term. Conclusions There were too few studies to assess whether stretching is effective compared to control or other interventions, for either pain or function. However, there is some evidence that plantar fascia stretching may be more effective than Achilles tendon stretching alone in the short-term. Appropriately powered randomised controlled trials, utilizing validated outcome

  14. Microbiome analysis shows enrichment for specific bacteria in separate anatomical regions of the deep-sea carnivorous sponge Chondrocladia grandis.

    Science.gov (United States)

    Verhoeven, Joost T P; Kavanagh, Alana N; Dufour, Suzanne C

    2017-01-01

    The Cladorhizidae is a unique family of carnivorous marine sponges characterised by either the absence or reduction of the aquiferous system and by the presence of specialised structures to trap and digest mesoplanktonic prey. Previous studies have postulated a key role of host-associated bacteria in enabling carnivory in this family of sponges. In this study, we employed high-throughput Illumina-based sequencing to identify the bacterial community associated with four individuals of the deep-sea sponge Chondrocladia grandis sampled in the Gulf of Maine. By characterising the V6 through V8 region of the 16S rRNA gene, we compared the bacterial community composition and diversity in three distinct anatomical regions with predicted involvement in prey capture (sphere), support (axis) and benthic substrate attachment (root). A high abundance of Tenacibaculum, a known siderophore producing bacterial genus, was present in all anatomical regions and specimens. The abundance of Colwellia and Roseobacter was greater in sphere and axis samples, and bacteria from the hydrocarbon-degrading Robiginitomaculum genus were most abundant in the root. This first description of the bacterial community associated with C. grandis provides novel insights into the contribution of bacteria to the carnivorous lifestyle while laying foundations for future cladorhizid symbiosis studies. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Bias of purine stretches in sequenced chromosomes

    DEFF Research Database (Denmark)

    Ussery, David; Soumpasis, Dikeos Mario; Brunak, Søren

    2002-01-01

    /pur tracts was slightly less than expected, with an average of 0.8%. One of the most surprising findings is a clear difference in the length distributions of the regions studied between prokaryotes and eukaryotes. Whereas short-range correlations can explain the length distributions in prokaryotes......, in eukaryotes there is an abundance of long stretches of purines or alternating purine/pyrimidine tracts, which cannot be explained in this way; these sequences are likely to play an important role in eukaryotic chromosome organisation....

  16. Transient filament stretching rheometer II

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1997-01-01

    The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

  17. Soleus stretch reflex during cycling

    DEFF Research Database (Denmark)

    Grey, Michael James; Pierce, C. W.; Milner, T. E.

    2001-01-01

    The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions durin...

  18. Optical tweezers stretching of chromatin

    NARCIS (Netherlands)

    Pope, L.H.; Bennink, Martin L.; Greve, Jan

    2003-01-01

    Recently significant success has emerged from exciting research involving chromatin stretching using optical tweezers. These experiments, in which a single chromatin fibre is attached by one end to a micron-sized bead held in an optical trap and to a solid surface or second bead via the other end,

  19. Vesper Sparrows and Western Meadowlarks Show a Mixed Response to Cattle Grazing in the Intermountain Region of British Columbia

    Directory of Open Access Journals (Sweden)

    Megan L. Harrison

    2010-06-01

    Full Text Available Livestock grazing in the shortgrass steppe of the Intermountain region of British Columbia is predicted to have significant effects on grassland habitats and their associated ground-nesting bird communities. We tested whether grazed and ungrazed sites could be discriminated on the basis of their vegetation communities, whether the abundance of two ground-nesting bird species, Vesper Sparrow (Pooecetes gramineus and Western Meadowlark (Sturnella neglecta, differed between grazed and ungrazed sites, and whether vegetation variables found to differ between grazed and ungrazed plots could be used to predict the abundance of the two bird species at a fine scale. Grazed sites were easily distinguishable from a site that had been ungrazed for >30 years based on the structure and composition of their vegetation communities. However, more detailed grazing categories could not be distinguished on the basis of vegetation characteristics. Despite the existence of grazing effects on vegetation structure and composition, we found no consistent differences in abundance of Vesper Sparrows and Western Meadowlarks between the grazed and ungrazed sites. However, there was weak evidence that the abundance of both species was higher at fine-scale plots (100 m radius point count station with less bare ground and taller vegetation. Bare ground cover was lower on grazed plots, but vegetation was taller on ungrazed plots. Combined, our results suggest that low intensity grazing leads to grassland habitat change with both negative and positive effects on Vesper Sparrows and Western Meadowlarks, resulting in no net change in their broad-scale abundance.

  20. Time stretch and its applications

    Science.gov (United States)

    Mahjoubfar, Ata; Churkin, Dmitry V.; Barland, Stéphane; Broderick, Neil; Turitsyn, Sergei K.; Jalali, Bahram

    2017-06-01

    Observing non-repetitive and statistically rare signals that occur on short timescales requires fast real-time measurements that exceed the speed, precision and record length of conventional digitizers. Photonic time stretch is a data acquisition method that overcomes the speed limitations of electronic digitizers and enables continuous ultrafast single-shot spectroscopy, imaging, reflectometry, terahertz and other measurements at refresh rates reaching billions of frames per second with non-stop recording spanning trillions of consecutive frames. The technology has opened a new frontier in measurement science unveiling transient phenomena in nonlinear dynamics such as optical rogue waves and soliton molecules, and in relativistic electron bunching. It has also created a new class of instruments that have been integrated with artificial intelligence for sensing and biomedical diagnostics. We review the fundamental principles and applications of this emerging field for continuous phase and amplitude characterization at extremely high repetition rates via time-stretch spectral interferometry.

  1. Analysis of a filament stretching rheometer

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1996-01-01

    A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown.......A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown....

  2. A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

    KAUST Repository

    Chang, Y.-H.

    2018-02-26

    Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non-planar transverse stretching process was employed in this study to produce micro-porous structure. The morphology, membrane thickness, mean pore size, and porosity of the PTFE membrane were investigated. The results show that the non-planar transverse stretched membranes exhibit more uniform average pore diameter with thinner membrane thickness. Morphological changes induced by planar and non-planar transverse stretching for pore characteristics were investigated. The stretching conditions, stretching temperature and rate, affect the stretched membrane. Increasing temperature facilitated the uniformity of pore size and uniformity of membrane thickness. Moreover, increase in stretching rate resulted in finer pore size and thinner membrane.

  3. Circumpolar assessment of rhizosphere priming shows limited increase in carbon loss estimates for permafrost soils but large regional variability

    Science.gov (United States)

    Wild, B.; Keuper, F.; Kummu, M.; Beer, C.; Blume-Werry, G.; Fontaine, S.; Gavazov, K.; Gentsch, N.; Guggenberger, G.; Hugelius, G.; Jalava, M.; Koven, C.; Krab, E. J.; Kuhry, P.; Monteux, S.; Richter, A.; Shazhad, T.; Dorrepaal, E.

    2017-12-01

    Predictions of soil organic carbon (SOC) losses in the northern circumpolar permafrost area converge around 15% (± 3% standard error) of the initial C pool by 2100 under the RCP 8.5 warming scenario. Yet, none of these estimates consider plant-soil interactions such as the rhizosphere priming effect (RPE). While laboratory experiments have shown that the input of plant-derived compounds can stimulate SOC losses by up to 1200%, the magnitude of RPE in natural ecosystems is unknown and no methods for upscaling exist so far. We here present the first spatial and depth explicit RPE model that allows estimates of RPE on a large scale (PrimeSCale). We combine available spatial data (SOC, C/N, GPP, ALT and ecosystem type) and new ecological insights to assess the importance of the RPE at the circumpolar scale. We use a positive saturating relationship between the RPE and belowground C allocation and two ALT-dependent rooting-depth distribution functions (for tundra and boreal forest) to proportionally assign belowground C allocation and RPE to individual soil depth increments. The model permits to take into account reasonable limiting factors on additional SOC losses by RPE including interactions between spatial and/or depth variation in GPP, plant root density, SOC stocks and ALT. We estimate potential RPE-induced SOC losses at 9.7 Pg C (5 - 95% CI: 1.5 - 23.2 Pg C) by 2100 (RCP 8.5). This corresponds to an increase of the current permafrost SOC-loss estimate from 15% of the initial C pool to about 16%. If we apply an additional molar C/N threshold of 20 to account for microbial C limitation as a requirement for the RPE, SOC losses by RPE are further reduced to 6.5 Pg C (5 - 95% CI: 1.0 - 16.8 Pg C) by 2100 (RCP 8.5). Although our results show that current estimates of permafrost soil C losses are robust without taking into account the RPE, our model also highlights high-RPE risk in Siberian lowland areas and Alaska north of the Brooks Range. The small overall impact of

  4. Effect of acute stretch injury on action potential and network activity of rat neocortical neurons in culture.

    Science.gov (United States)

    Magou, George C; Pfister, Bryan J; Berlin, Joshua R

    2015-10-22

    The basis for acute seizures following traumatic brain injury (TBI) remains unclear. Animal models of TBI have revealed acute hyperexcitablility in cortical neurons that could underlie seizure activity, but studying initiating events causing hyperexcitability is difficult in these models. In vitro models of stretch injury with cultured cortical neurons, a surrogate for TBI, allow facile investigation of cellular changes after injury but they have only demonstrated post-injury hypoexcitability. The goal of this study was to determine if neuronal hyperexcitability could be triggered by in vitro stretch injury. Controlled uniaxial stretch injury was delivered to a spatially delimited region of a spontaneously active network of cultured rat cortical neurons, yielding a region of stretch-injured neurons and adjacent regions of non-stretched neurons that did not directly experience stretch injury. Spontaneous electrical activity was measured in non-stretched and stretch-injured neurons, and in control neuronal networks not subjected to stretch injury. Non-stretched neurons in stretch-injured cultures displayed a three-fold increase in action potential firing rate and bursting activity 30-60 min post-injury. Stretch-injured neurons, however, displayed dramatically lower rates of action potential firing and bursting. These results demonstrate that acute hyperexcitability can be observed in non-stretched neurons located in regions adjacent to the site of stretch injury, consistent with reports that seizure activity can arise from regions surrounding the site of localized brain injury. Thus, this in vitro procedure for localized neuronal stretch injury may provide a model to study the earliest cellular changes in neuronal function associated with acute post-traumatic seizures. Copyright © 2015. Published by Elsevier B.V.

  5. A Japanese Stretching Intervention Can Modify Lumbar Lordosis Curvature.

    Science.gov (United States)

    Kadono, Norio; Tsuchiya, Kazushi; Uematsu, Azusa; Kamoshita, Hiroshi; Kiryu, Kazunori; Hortobágyi, Tibor; Suzuki, Shuji

    2017-08-01

    Eighteen healthy male adults were assigned to either an intervention or control group. Isogai dynamic therapy (IDT) is one of Japanese stretching interventions and has been practiced for over 70 years. However, its scientific quantitative evidence remains unestablished. The objective of this study was to determine whether IDT could modify lumbar curvature in healthy young adults compared with stretching exercises used currently in clinical practice. None of previous studies have provided data that conventional stretching interventions could modify spinal curvatures. However, this study provides the first evidence that a specific form of a Japanese stretching intervention can acutely modify the spinal curvatures. We compared the effects of IDT, a Japanese stretching intervention (n=9 males), with a conventional stretching routine (n=9 males) used widely in clinics to modify pelvic tilt and lumbar lordosis (LL) angle. We measured thoracic kyphosis (TK) and LL angles 3 times during erect standing using the Spinal Mouse before and after each intervention. IDT consisted of: (1) hip joint correction, (2) pelvic tilt correction, (3) lumbar alignment correction, and (4) squat exercise stretch. The control group performed hamstring stretches while (1) standing and (2) sitting. IDT increased LL angle to 25.1 degrees (±5.9) from 21.2 degrees (±6.9) (P=0.047) without changing TK angle (pretest: 36.8 degrees [±6.9]; posttest: 36.1 degrees [±6.5]) (P=0.572). The control group showed no changes in TK (P=0.819) and LL angles (P=0.744). IDT can thus be effective for increasing LL angle, hence anterior pelvic tilt. Such modifications could ameliorate low back pain and improve mobility in old adults with an unfavorable pelvic position.

  6. Efficacy of hamstring stretching programs in schoolchildren. A systematic review

    Directory of Open Access Journals (Sweden)

    Carlos-Alberto BECERRA FERNANDEZ

    2017-03-01

    Full Text Available The main purpose of the present review was to examine the scientific literature on the effects of physical education-based stretching programs on hamstring extensibility in schoolchildren aged 6-11 years. For this purpose relevant studies were searched from ten electronic databases dated up through May 2015. Of the 25 potentially relevant articles identified and retrieved for more detailed evaluation, only eight studies were included in the present review because they met the inclusion criteria. The overall results showed that incorporating hamstring stretching as a part of physical education classes produces a significant improvement in the scores of the tests: straight leg raise and classic sit-and-reach, for the experimental groups, but not for control groups. Stretching programs can be included in Physical Education classes, specifically during the warm-up and the cool down periods in order to improve hamstring extensibility. Although it seems that the stretching exercises in the warm-up period could be less effective in gaining flexibility in school children. Studies that use a stretching volume between 4 and 7 minutes per session and 2-4 training classes per week, obtain statistically significant improvements on the levels of hamstring flexibility in the experimental groups. However, after a five-week detraining period, children revert back to their initial flexibility levels. Therefore, it seems appropriate that physical education teachers should implement stretching programs to improve the students´ flexibility during the Physical Education classes.

  7. Effects of stretching and compression on conducting properties of an Au–alkanedithiol–Au molecular junction

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Fang; Zhang, Xiao-Jiao; Yu, Ji-Hai; Xu, Hua; Chu, Yu-Fang [Physics Science and Engineering Technology College, Yichun University, Yichun 336000 (China); Fan, Zhi-Qiang, E-mail: fan0221@163.com [School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410004 (China)

    2016-03-01

    We have studied the effects of stretching and compression on the electronic properties of 7-alkanedithiol covalently linked to two Au electrodes. Results show a progressive increase in conductivity upon molecule compression and decrease with molecule stretching. The notable conductance increase at high compression is attributed to a significant modification of HOMO and LUMO orbitals of the junction, which enhances electron delocalization and promotes tunneling across the junction. More important, the current switching ratios between the various stages of compressed/extended geometries almost maintain the constant values on the bias region from 0 V to 2 V. In other word, the mechanically-induced conductance enhancement and weakening are stable within a large bias voltage range.

  8. Endovascular rescue method for undesirably stretched coil.

    Science.gov (United States)

    Cho, Jae Hoon

    2014-10-01

    Undesirable detachment or stretching of coils within the parent artery during aneurysm embolization can be related with thrombus formation, which can be caused occlusion of parent artery or embolic event(s). To escape from this situation, several rescue methods have been reported. A case with undesirably stretched coil in which another rescue method was used, is presented. When the stretched coil is still located in the coil delivery microcatheter, the stretched coil can be removed safely using a snare and a handmade monorail microcatheter. After a snare is lodged in the handmade monorail microcatheter, the snare is introduced over the coil delivery micorcatheter and located in the distal part of the stretched coil. After then, the handmade monorail microcatheter captures the stretched coil and the snare as one unit. This technique using a handmade monorail microcatheter and a snare can be a good rescue modality for the undesirably stretched coil, still remained within the coil delivery microcatheter.

  9. Probabilistic model of ligaments and tendons: Quasistatic linear stretching

    Science.gov (United States)

    Bontempi, M.

    2009-03-01

    Ligaments and tendons have a significant role in the musculoskeletal system and are frequently subjected to injury. This study presents a model of collagen fibers, based on the study of a statistical distribution of fibers when they are subjected to quasistatic linear stretching. With respect to other methodologies, this model is able to describe the behavior of the bundle using less ad hoc hypotheses and is able to describe all the quasistatic stretch-load responses of the bundle, including the yield and failure regions described in the literature. It has two other important results: the first is that it is able to correlate the mechanical behavior of the bundle with its internal structure, and it suggests a methodology to deduce the fibers population distribution directly from the tensile-test data. The second is that it can follow fibers’ structure evolution during the stretching and it is possible to study the internal adaptation of fibers in physiological and pathological conditions.

  10. Bending and stretching of plates

    CERN Document Server

    Mansfield, E H; Hemp, W S

    1964-01-01

    The Bending and Stretching of Plates deals with elastic plate theory, particularly on small- and large-deflexion theory. Small-deflexion theory concerns derivation of basic equations, rectangular plates, plates of various shapes, plates whose boundaries are amenable to conformal transformation, plates with variable rigidity, and approximate methods. Large-deflexion theory includes general equations and some exact solutions, approximate methods in large-deflexion theory, asymptotic large-deflexion theories for very thin plates. Asymptotic theories covers membrane theory, tension field theory, a

  11. Stretching of macromolecules and proteins

    International Nuclear Information System (INIS)

    Strick, T R; Dessinges, M-N; Charvin, G; Dekker, N H; Allemand, J-F; Bensimon, D; Croquette, V

    2003-01-01

    In this paper we review the biophysics revealed by stretching single biopolymers. During the last decade various techniques have emerged allowing micromanipulation of single molecules and simultaneous measurements of their elasticity. Using such techniques, it has been possible to investigate some of the interactions playing a role in biology. We shall first review the simplest case of a non-interacting polymer and then present the structural transitions in DNA, RNA and proteins that have been studied by single-molecule techniques. We shall explain how these techniques permit a new approach to the protein folding/unfolding transition

  12. To Stretch and Search for Better Ways

    Science.gov (United States)

    Moore, John W.

    2000-06-01

    Ambassadors. The response has been wonderful. Many people are willing and eager to show others what JCE has to offer and encourage them to subscribe. The program began in the latter half of 1999, and there were 37 Journal Ambassadors by year's end. Some are located as far away as South America and Europe, and requests for information packets for meetings and workshops now arrive several times a week. We thank everyone who has been involved in this program for getting it off to a great start. Our authors and reviewers actively search for better ways to teach chemistry and for better ways to communicate to other teachers what they have learned. This enriches their own classes first and then a much wider audience. Others have volunteered to help make JCE articles easier to find and more accessible on the Web. The ACS student affiliates at one college have taken on the project of assigning keywords to articles published in some of the years before 1995. We will add these to the JCE Index online, making it an even more effective means for finding articles on specified topics. There are many possibilities for collaboration with JCE. If you would like to contribute to an ongoing project or would like to initiate a new one, please let us know. We welcome anyone who would like to help us make this Journal better. It is important that students learn how to stretch and search for better ways. This will not happen unless we challenge them within a humane and supportive learning environment. We should expect more than memorization or unthinking application of algorithmic solutions to exercises. We should provide means by which those who do not succeed at first can try again and again. And we should provide an intellectual scaffold for those whose climb toward understanding is difficult. These are not easy goals to achieve, but the more we try and the more we communicate with others who are attempting similar tasks, the more likely we are to be successful. Most important of all is that

  13. The acute effect of static and dynamic stretching during warm-ups on anaerobic performance in trained women

    Directory of Open Access Journals (Sweden)

    rouhollah haghshenas

    2014-09-01

    Full Text Available The purpose of this study was to investigate effects of static stretching, dynamic stretching and no stretching methods on power and speed in volleyball players. Therefore, Twenty-four volleyball players (height: 173.29 ± 7.81 m; mass: 62.12 ± 8.73 kg; age: 22.66 ± 4.02 years; experience: 3.27 ± 6.37 were tested for speed performance using the 20 meter sprint test and also for power using vertical jump test after static stretching, dynamic stretching and no stretching. The results analyzed using ANOVA showed that There was a significant increase in height jump after dynamic stretching against static stretching. But, there were no significant differences between no stretching and static stretching groups. In addition, there was a significant decrease in time 20 meter sprint after dynamic stretching against static stretching and no stretching groups. The results of this study suggest that it may be desirable for volleyball players to perform dynamic exercises before the performance of activities that require a high power output.

  14. Biaxial stretching of film principles and applications

    CERN Document Server

    Demeuse, M T

    2011-01-01

    Biaxial (having two axes) stretching of film is used for a range of applications and is the primary manufacturing process by which products are produced for the food packaging industry. Biaxial stretching of film: principles and applications provides an overview of the manufacturing processes and range of applications for biaxially stretched films. Part one reviews the fundamental principles of biaxial stretching. After an introductory chapter which defines terms, chapters discuss equipment design and requirements, laboratory evaluations, biaxial film structures and typical industrial processes for the biaxial orientation of films. Additional topics include post production processing of biaxially stretched films, the stress-strain behaviour of poly(ethylene terephthalate) and academic investigations of biaxially stretched films. Part two investigates the applications of biaxial films including fresh cut produce, snack packaging and product labelling. A final chapter investigates potential future trends for bi...

  15. Effects of special composite stretching on the swing of amateur golf players.

    Science.gov (United States)

    Lee, Joong-Chul; Lee, Sung-Wan; Yeo, Yun-Ghi; Park, Gi Duck

    2015-04-01

    [Purpose] The study investigated stretching for safer a golf swing compared to present stretching methods for proper swings in order to examine the effects of stretching exercises on golf swings. [Subjects] The subjects were 20 amateur golf club members who were divided into two groups: an experimental group which performed stretching, and a control group which did not. The subjects had no bone deformity, muscle weakness, muscle soreness, or neurological problems. [Methods] A swing analyzer and a ROM measuring instrument were used as the measuring tools. The swing analyzer was a GS400-golf hit ball analyzer (Korea) and the ROM measuring instrument was a goniometer (Korea). [Results] The experimental group showed a statistically significant improvement in driving distance. After the special stretching training for golf, a statistically significant difference in hit-ball direction deviation after swings were found between the groups. The experimental group showed statistically significant decreases in hit ball direction deviation. After the special stretching training for golf, statistically significant differences in hit-ball speed were found between the groups. The experimental group showed significant increases in hit-ball speed. [Conclusion] To examine the effects of a special stretching program for golf on golf swing-related factors, 20 male amateur golf club members performed a 12-week stretching training program. After the golf stretching training, statistically significant differences were found between the groups in hit-ball driving distance, direction deviation, deflection distance, and speed.

  16. EFFECT OF DIFFERENT STRETCHING PROTOCOLS ON VERTICAL JUMP PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Emre Serin

    2018-04-01

    Full Text Available This study aimed to examine the effect of different stretching exercises on vertical jump performance. A total of 14 national male athletes sporting in the elite level took part in the study. The age average of the participants was 20.25±1.03 year, the average height was 1.80±.08 m, the average body weight was 77.14±18.91 kg, average of sporting age was 9.87±3.31 year and the average number of participation in international games was 10.0±3.31. As stretching protocol: Method 1 (5 minutes of jogging and 2 minutes of active rest followed by Method 2 (static stretching for 4 different muscle groups 3 repetitions for 15 seconds of static stretching, rest for 10 seconds between groups and then consecutively, Method 3 (Dynamic stretching exercises with 3 repetitions for 15 seconds and 10 seconds rest between different muscle groups were applied in the study. The vertical jump performance before and after different stretching exercises of the participants was determined by means of the vertical jump test using the smart speed lite system. Before and after the training of all athletes, HR was recorded with a heart rate monitor (RS 800, Polar Vantage NV, Polar Electro Oy, Finland with 5 seconds intervals. Before the study, the chest band of the heartbeat monitor was placed on the chest of the athlete and the HR was recorded from the monitor. SPSS 15.0 statistical package program was used for evaluation and calculation of the data. In this study in addition to descriptive statistics (mean and standard deviation paired samples t-test was used to determine the difference between the vertical jump performance of the participants before and after different stretching exercises. As a result, this study showed that; applying the dynamic and static stretching exercises consecutively affected the vertical jump performance 4.5 cm positively (p<.05. It is suggested that different dynamic and static stretching exercises should be included in the vertical jump.

  17. Linear viscoelastic characterization from filament stretching rheometry

    DEFF Research Database (Denmark)

    Wingstrand, Sara Lindeblad; Alvarez, Nicolas J.; Hassager, Ole

    to measure both linear and nonlinear dynamics on a single apparatus. With a software modification to the FSR motor control, we show that linear viscoelasticity can be measured via small amplitude squeeze flow (SASF). Squeeze flow is a combination of both shear and extensional flow applied by axially......Traditionally, linear viscoelasticity is measured using small amplitude oscillatory shear flow. Due to experimental difficulties, shear flows are predominately confined to the linear and mildly nonlinear regime. On the other hand, extensional flows have proven more practical in measuring...... viscoelasticity well into the nonlinear regime. Therefore at present, complete rheological characterization of a material requires two apparatuses: a shear and an extensional rheometer. This work is focused on developing a linear viscoelastic protocol for the filament stretching rheometer (FSR) in order...

  18. Stretching and jamming of finite automata

    NARCIS (Netherlands)

    Beijer, de N.; Kourie, D.G.; Watson, B.W.; Cleophas, L.G.W.A.; Watson, B.W.

    2004-01-01

    In this paper we present two transformations on automata, called stretching and jamming. These transformations will, under certain conditions, reduce the size of the transition table, and under other conditions reduce the string processing time. Given a finite automaton, we can stretch it by

  19. Enhanced Age Strengthening of Mg-Nd-Zn-Zr Alloy via Pre-Stretching

    Directory of Open Access Journals (Sweden)

    Erjun Guo

    2016-08-01

    Full Text Available Pre-stretching was carried out to modify the microstructure of Mg-Nd-Zn-Zr alloy to enhance its age strengthening. The results indicated that more heterogeneous nucleation sites can be provided by the high density of dislocations caused by the plastic pre-stretching deformation, as well as speeding up the growth rate of precipitates. Comparison of microstructure in non-pre-stretched specimens after artificial aging showed that pre-stretched specimens exhibited a higher number density of precipitates. The fine and coarse plate-shaped precipitates were found in the matrix. Due to an increase in the number density of precipitates, the dislocation slipping during the deformation process is effectively hindered, and the matrix is strengthened. The yield strength stabilizes at 4% pre-stretching condition, and then the evolution is stable within the error bars. The 8% pre-stretched specimens can achieve an ultimate tensile strength of 297 MPa. However, further pre-stretching strains after 8% cannot supply any increase in strength. Tensile fracture surfaces of specimens subjected to pre-stretching strain mainly exhibit a trans-granular cleavage fracture. This work indicated that a small amount of pre-stretching strain can further increase strength of alloy and also effectively enhance the formation of precipitates, which can expand the application fields of this alloy.

  20. Strategy as stretch and leverage.

    Science.gov (United States)

    Hamel, G; Prahalad, C K

    1993-01-01

    Global competition is not just product versus product or company versus company. It is mind-set versus mind-set. Driven to understand the dynamics of competition, we have learned a lot about what makes one company more successful than another. But to find the root of competitiveness--to understand why some companies create new forms of competitive advantage while others watch and follow--we must look at strategic mind-sets. For many managers, "being strategic" means pursuing opportunities that fit the company's resources. This approach is not wrong, Gary Hamel and C.K. Prahalad contend, but it obscures an approach in which "stretch" supplements fit and being strategic means creating a chasm between ambition and resources. Toyota, CNN, British Airways, Sony, and others all displaced competitors with stronger reputations and deeper pockets. Their secret? In each case, the winner had greater ambition than its well-endowed rivals. Winners also find less resource-intensive ways of achieving their ambitious goals. This is where leverage complements the strategic allocation of resources. Managers at competitive companies can get a bigger bang for their buck in five basic ways: by concentrating resources around strategic goals; by accumulating resources more efficiently; by complementing one kind of resource with another; by conserving resources whenever they can; and by recovering resources from the market-place as quickly as possible. As recent competitive battles have demonstrated, abundant resources can't guarantee continued industry leadership.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Stretching skeletal muscle: chronic muscle lengthening through sarcomerogenesis.

    Directory of Open Access Journals (Sweden)

    Alexander M Zöllner

    Full Text Available Skeletal muscle responds to passive overstretch through sarcomerogenesis, the creation and serial deposition of new sarcomere units. Sarcomerogenesis is critical to muscle function: It gradually re-positions the muscle back into its optimal operating regime. Animal models of immobilization, limb lengthening, and tendon transfer have provided significant insight into muscle adaptation in vivo. Yet, to date, there is no mathematical model that allows us to predict how skeletal muscle adapts to mechanical stretch in silico. Here we propose a novel mechanistic model for chronic longitudinal muscle growth in response to passive mechanical stretch. We characterize growth through a single scalar-valued internal variable, the serial sarcomere number. Sarcomerogenesis, the evolution of this variable, is driven by the elastic mechanical stretch. To analyze realistic three-dimensional muscle geometries, we embed our model into a nonlinear finite element framework. In a chronic limb lengthening study with a muscle stretch of 1.14, the model predicts an acute sarcomere lengthening from 3.09[Formula: see text]m to 3.51[Formula: see text]m, and a chronic gradual return to the initial sarcomere length within two weeks. Compared to the experiment, the acute model error was 0.00% by design of the model; the chronic model error was 2.13%, which lies within the rage of the experimental standard deviation. Our model explains, from a mechanistic point of view, why gradual multi-step muscle lengthening is less invasive than single-step lengthening. It also explains regional variations in sarcomere length, shorter close to and longer away from the muscle-tendon interface. Once calibrated with a richer data set, our model may help surgeons to prevent muscle overstretch and make informed decisions about optimal stretch increments, stretch timing, and stretch amplitudes. We anticipate our study to open new avenues in orthopedic and reconstructive surgery and enhance

  2. Theory of high-force DNA stretching and overstretching.

    Science.gov (United States)

    Storm, C; Nelson, P C

    2003-05-01

    Single-molecule experiments on single- and double-stranded DNA have sparked a renewed interest in the force versus extension of polymers. The extensible freely jointed chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded DNA, but this model does not satisfactorily describe recent high-force stretching data. We instead propose a model (the discrete persistent chain) that borrows features from both the FJC and the wormlike chain, and show that it resembles the data more closely. We find that most of the high-force behavior previously attributed to stretch elasticity is really a feature of the corrected entropic elasticity; the true stretch compliance of single-stranded DNA is several times smaller than that found by previous authors. Next we elaborate our model to allow coexistence of two conformational states of DNA, each with its own stretch and bend elastic constants. Our model is computationally simple and gives an excellent fit through the entire overstretching transition of nicked, double-stranded DNA. The fit gives the first value for the bend stiffness of the overstretched state. In particular, we find the effective bend stiffness for DNA in this state to be about 12 nm k(B)T, a value quite different from either the B-form or single-stranded DNA.

  3. Stretched versus compressed exponential kinetics in α-helix folding

    International Nuclear Information System (INIS)

    Hamm, Peter; Helbing, Jan; Bredenbeck, Jens

    2006-01-01

    In a recent paper (J. Bredenbeck, J. Helbing, J.R. Kumita, G.A. Woolley, P. Hamm, α-helix formation in a photoswitchable peptide tracked from picoseconds to microseconds by time resolved IR spectroscopy, Proc. Natl. Acad. Sci USA 102 (2005) 2379), we have investigated the folding of a photo-switchable α-helix with a kinetics that could be fit by a stretched exponential function exp(-(t/τ) β ). The stretching factor β became smaller as the temperature was lowered, a result which has been interpreted in terms of activated diffusion on a rugged energy surface. In the present paper, we discuss under which conditions diffusion problems occur with stretched exponential kinetics (β 1). We show that diffusion problems do have a strong tendency to yield stretched exponential kinetics, yet, that there are conditions (strong perturbation from equilibrium, performing the experiment in the folding direction) under which compressed exponential kinetics would be expected instead. We discuss the kinetics on free energy surfaces predicted by simple initiation-propagation models (zipper models) of α-helix folding, as well as by folding funnel models. We show that our recent experiment has been performed under condition for which models with strong downhill driving force, such as the zipper model, would predict compressed, rather than stretched exponential kinetics, in disagreement with the experimental observation. We therefore propose that the free energy surface along a reaction coordinate that governs the folding kinetics must be relatively flat and has a shape similar to a 1D golf course. We discuss how this conclusion can be unified with the thermodynamically well established zipper model by introducing an additional kinetic reaction coordinate

  4. Investing in a Large Stretch Press

    Science.gov (United States)

    Choate, M.; Nealson, W.; Jay, G.; Buss, W.

    1986-01-01

    Press for forming large aluminum parts from plates provides substantial economies. Study assessed advantages and disadvantages of investing in large stretch-forming press, and also developed procurement specification for press.

  5. Excluded Volume Effects in Gene Stretching

    OpenAIRE

    Lam, Pui-Man

    2002-01-01

    We investigate the effects excluded volume on the stretching of a single DNA in solution. We find that for small force F, the extension h is not linear in F but proportion to F^{\\chi}, with \\chi=(1-\

  6. Motor units in vastus lateralis and in different vastus medialis regions show different firing properties during low-level, isometric knee extension contraction.

    Science.gov (United States)

    de Souza, Leonardo Mendes Leal; Cabral, Hélio Veiga; de Oliveira, Liliam Fernandes; Vieira, Taian Martins

    2018-04-01

    Architectural differences along vastus medialis (VM) and between VM and vastus lateralis (VL) are considered functionally important for the patellar tracking, knee joint stability and knee joint extension. Whether these functional differences are associated with a differential activity of motor units between VM and VL is however unknown. In the present study, we, therefore, investigate neuroanatomical differences in the activity of motor units detected proximo-distally from VM and from the VL muscle. Nine healthy volunteers performed low-level isometric knee extension contractions (20% of their maximum voluntary contraction) following a trapezoidal trajectory. Surface electromyograms (EMGs) were recorded from VM proximal and distal regions and from VL using three linear adhesive arrays of eight electrodes. The firing rate and recruitment threshold of motor units decomposed from EMGs were then compared among muscle regions. Results show that VL motor units reached lower mean firing rates in comparison with VM motor units, regardless of their position within VM (P motor units (P = .997). Furthermore, no significant differences in the recruitment threshold were observed for all motor units analysed (P = .108). Our findings possibly suggest the greater potential of VL to generate force, due to its fibres arrangement, may account for the lower discharge rate observed for VL then either proximally or distally detected motor units in VM. Additionally, the present study opens new perspectives on the importance of considering muscle architecture in investigations of the neural aspects of motor behaviour. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. [Current trends in the effects of stretching: application to physical exercise in the workplace].

    Science.gov (United States)

    Eguchi, Yasumasa; Ohta, Masanori; Yamato, Hiroshi

    2011-09-01

    A review of the Survey on the State of Employees' Health by the Ministry of Health, Labour and Welfare (2008) shows that the most commonly implemented aspect as an activity of worksite health promotion is "Health counseling", and the second is "Workplace physical exercise." Physical exercise, "Taiso", is acceptable and sustainable for workers, as it is easy to do in a group or alone. Various modes of stretching are implemented for workplace physical exercise. However, articles suggesting negative or contradictory effects of stretching have increased in recent years. Several review articles have revealed that static stretching may induce impairments of muscle power performance and no stretching will prevent or reduce muscle soreness after exercise. There are various aims of workplace physical exercise, so we have to consider the situational method when we apply stretching to occupational health.

  8. Stretch induced endothelin-1 secretion by adult rat astrocytes involves calcium influx via stretch-activated ion channels (SACs)

    International Nuclear Information System (INIS)

    Ostrow, Lyle W.; Suchyna, Thomas M.; Sachs, Frederick

    2011-01-01

    Highlights: → Endothelin-1 expression by adult rat astrocytes correlates with cell proliferation. → Stretch-induced ET-1 is inhibited by GsMtx-4, a specific inhibitor of Ca 2+ permeant SACs. → The less specific SAC inhibitor streptomycin also inhibits ET-1 secretion. → Stretch-induced ET-1 production depends on a calcium influx. → SAC pharmacology may provide a new class of therapeutic agents for CNS pathology. -- Abstract: The expression of endothelins (ETs) and ET-receptors is often upregulated in brain pathology. ET-1, a potent vasoconstrictor, also inhibits the expression of astrocyte glutamate transporters and is mitogenic for astrocytes, glioma cells, neurons, and brain capillary endothelia. We have previously shown that mechanical stress stimulates ET-1 production by adult rat astrocytes. We now show in adult astrocytes that ET-1 production is driven by calcium influx through stretch-activated ion channels (SACs) and the ET-1 production correlates with cell proliferation. Mechanical stimulation using biaxial stretch ( 2+ threshold. This coupling of mechanical stress to the astrocyte endothelin system through SACs has treatment implications, since all pathology deforms the surrounding parenchyma.

  9. Mechanical stretch modulates microRNA 21 expression, participating in proliferation and apoptosis in cultured human aortic smooth muscle cells.

    Directory of Open Access Journals (Sweden)

    Jian tao Song

    Full Text Available OBJECTIVES: Stretch affects vascular smooth muscle cell proliferation and apoptosis, and several responsible genes have been proposed. We tested whether the expression of microRNA 21 (miR-21 is modulated by stretch and is involved in stretch-induced proliferation and apoptosis of human aortic smooth muscle cells (HASMCs. METHODS AND RESULTS: RT-PCR revealed that elevated stretch (16% elongation, 1 Hz increased miR-21 expression in cultured HASMCs, and moderate stretch (10% elongation, 1 Hz decreased the expression. BrdU incorporation assay and cell counting showed miR-21 involved in the proliferation of HASMCs mediated by stretch, likely by regulating the expression of p27 and phosphorylated retinoblastoma protein (p-Rb. FACS analysis revealed that the complex of miR-21 and programmed cell death protein 4 (PDCD4 participated in regulating apoptosis with stretch. Stretch increased the expression of primary miR-21 and pre-miR-21 in HASMCs. Electrophoretic mobility shift assay (EMSA demonstrated that stretch increased NF-κB and AP-1 activities in HASMCs, and blockade of AP-1 activity by c-jun siRNA significantly suppressed stretch-induced miR-21 expression. CONCLUSIONS: Cyclic stretch modulates miR-21 expression in cultured HASMCs, and miR-21 plays important roles in regulating proliferation and apoptosis mediated by stretch. Stretch upregulates miR-21 expression at least in part at the transcription level and AP-1 is essential for stretch-induced miR-21 expression.

  10. The Effect of Static Stretch on Elastin Degradation in Arteries

    Science.gov (United States)

    Chow, Ming-Jay; Choi, Myunghwan; Yun, Seok Hyun; Zhang, Yanhang

    2013-01-01

    Previously we have shown that gradual changes in the structure of elastin during an elastase treatment can lead to important transition stages in the mechanical behavior of arteries [1]. However, in vivo arteries are constantly being loaded due to systolic and diastolic pressures and so understanding the effects of loading on the enzymatic degradation of elastin in arteries is important. With biaxial tensile testing, we measured the mechanical behavior of porcine thoracic aortas digested with a mild solution of purified elastase (5 U/mL) in the presence of a static stretch. Arterial mechanical properties and biochemical composition were analyzed to assess the effects of mechanical stretch on elastin degradation. As elastin is being removed, the dimensions of the artery increase by more than 20% in both the longitude and circumference directions. Elastin assays indicate a faster rate of degradation when stretch was present during the digestion. A simple exponential decay fitting confirms the time constant for digestion with stretch (0.11±0.04 h−1) is almost twice that of digestion without stretch (0.069±0.028 h−1). The transition from J-shaped to S-shaped stress vs. strain behavior in the longitudinal direction generally occurs when elastin content is reduced by about 60%. Multiphoton image analysis confirms the removal/fragmentation of elastin and also shows that the collagen fibers are closely intertwined with the elastin lamellae in the medial layer. After removal of elastin, the collagen fibers are no longer constrained and become disordered. Release of amorphous elastin during the fragmentation of the lamellae layers is observed and provides insights into the process of elastin degradation. Overall this study reveals several interesting microstructural changes in the extracellular matrix that could explain the resulting mechanical behavior of arteries with elastin degradation. PMID:24358135

  11. Effect of CH stretching excitation on the reaction dynamics of F + CHD{sub 3} → DF + CHD{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jiayue; Zhang, Dong; Chen, Zhen; Jiang, Bo [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Blauert, Florian [Dynamics at Surfaces, Faculty of Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen (Germany); Dai, Dongxu; Wu, Guorong, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Zhang, Donghui; Yang, Xueming, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-07-28

    The vibrationally excited reaction of F + CHD{sub 3}(ν{sub 1} = 1) → DF + CHD{sub 2} at a collision energy of 9.0 kcal/mol is investigated using the crossed-beams and time-sliced velocity map imaging techniques. Detailed and quantitative information of the CH stretching excitation effects on the reactivity and dynamics of the title reaction is extracted with the help of an accurate determination of the fraction of the excited CHD{sub 3} reagent in the crossed-beam region. It is found that all vibrational states of the CHD{sub 2} products observed in the ground-state reaction, which mainly involve the excitation of the umbrella mode of the CHD{sub 2} products, are severely suppressed by the CH stretching excitation. However, there are four additional vibrational states of the CHD{sub 2} products appearing in the excited-state reaction which are not presented in the ground-state reaction. These vibrational states either have the CH stretching excitation retained or involve one quantum excitation in the CH stretching and the excitation of the umbrella mode. Including all observed vibrational states, the overall cross section of the excited-state reaction is estimated to be 66.6% of that of the ground-state one. Experimental results also show that when the energy of CH stretching excitation is released during the reaction, it is deposited almost exclusively as the rovibrational energy of the DF products, with little portion in the translational degree of freedom. For vibrational states of the CHD{sub 2} products observed in both ground- and excited-state reactions, the CH stretching excitation greatly suppresses the forward scattered products, causing a noticeable change in the product angular distributions.

  12. Foliar δ13C Showed No Altitudinal Trend in an Arid Region and Atmospheric Pressure Exerted a Negative Effect on Plant δ13C

    Directory of Open Access Journals (Sweden)

    Zixun Chen

    2017-07-01

    Full Text Available Previous studies have suggested foliar δ13C generally increases with altitude. However, some observations reported no changes or even decreased trends in foliar δ13C. We noted that all the studies in which δ13C increased with elevation were conducted in the human regions, whereas those investigations in which δ13C did not vary or decreased were conducted in areas with water stress. Thus, we proposed that the pattern of increasing δ13C with elevation is not a general one, and that δ13C may remain unchanged or decrease in plants grown in arid environments. To test the hypothesis, we sampled plants along altitude gradients on the shady and sunny slopes of Mount Tianshan characterized by arid and semiarid climates. The measurements of foliar δ13C showed no altitudinal trends for the plants grown on either of the slopes. Therefore, this study supported our hypothesis. In addition, the present study addressed the effect of atmospheric pressure on plant δ13C by accounting for the effects of temperature and precipitation on δ13C. This study found that the residual foliar δ13C increased with increasing altitude, suggesting that atmospheric pressure played a negative role in foliar δ13C.

  13. Anomalies in the coil-stretch transition of flexible polymers

    Science.gov (United States)

    Ghosal, Aishani; Cherayil, Binny J.

    2018-03-01

    The flow-induced coil-stretch transition of high molecular weight polymers has generally been held to be of first order. But evidence of significant slowing down in the rate at which the polymers relax to equilibrium in the vicinity of the transition suggests that the thermodynamic character of the transition may be less clear-cut. The above slowing down effect is actually characteristic of a second-order transition, and it points to the existence of a broad spectrum of conformational states in the transition region, analogous to the existence of fluctuations of all length scales at a critical point. In this paper, using a path integral approach based on a free-draining finitely extensible chain model, we calculate various polymer properties as a function of elongational flow as a way of exploring different statistical mechanical details of the coil-stretch transition. These properties include the molecular weight dependence of the flow-extension curve of the polymer, the distribution of its steady-state end-to-end distances, and the characteristic relaxation time τR of these distances. Among other findings, our calculations indicate that the coil-stretch transition is discontinuous in the N → ∞ limit, that the effective free energy of the chain is unimodal at all values of the flow, becoming broad and flat in the immediate vicinity of the transition, and that the ratio of τR to the Rouse relaxation time increases abruptly at the transition before eventually reaching a plateau value at large flow strengths. These aspects of the coil-stretch transition place it among a larger class of unconventional nominally first-order single chain transitions that include the adsorption transition of surface-tethered polymers and the escape transition of compressed polymers.

  14. Influence of the stretch wrapping process on the mechanical behavior of a stretch film

    Science.gov (United States)

    Klein, Daniel; Stommel, Markus; Zimmer, Johannes

    2018-05-01

    Lightweight construction is an ongoing task in packaging development. Consequently, the stability of packages during transport is gaining importance. This study contributes to the optimization of lightweight packaging concepts regarding their stability. A very widespread packaging concept is the distribution of goods on a pallet whereas a Polyethylene (PE) stretch film stabilizes the lightweight structure during the shipment. Usually, a stretch wrapping machine applies this stretch film to the pallet. The objective of this study is to support packaging development with a method that predicts the result of the wrapping process, based on the mechanical characterization of the stretch film. This result is not only defined by the amount of stretch film, its spatial distribution on the pallet and its internal stresses that result in a containment force. More accurate, this contribution also considers the influence of the deformation history of the stretch film during the wrapping process. By focusing on similarities of stretch wrappers rather than on differences, the influence of generalized process parameters on stretch film mechanics and thereby on pallet stability can be determined experimentally. For a practical use, the predictive method is accumulated in an analytic model of the wrapping process that can be verified experimentally. This paves the way for experimental and numerical approaches regarding the optimization of pallet stability.

  15. The Considere condition and rapid stretching of linear and branched polymer melts

    DEFF Research Database (Denmark)

    McKinley, Gareth H; Hassager, Ole

    1999-01-01

    to larger Hencky strains as the number of branches is increased. Numerical computations at finite Deborah numbers also show that there is an optimal range of deformation rates over which homogeneous extensions can be maintained to large strain. We also consider other rapid homogeneous stretching...... deformations, such as biaxial and planar stretching, and show that the degree of stabilization afforded by inclusion of material with long-chain branching is a sensitive function of the imposed mode of deformation....

  16. Effect of Strain Rate on Microscopic Deformation Behavior of High-density Polyethylene under Uniaxial Stretching

    Directory of Open Access Journals (Sweden)

    Kida Takumitsu

    2017-01-01

    Full Text Available The microscopic deformation behaviors such as the load sharing and the molecular orientation of high-density polyethylene under uniaxial stretching at various strain rates were investigated by using in-situ Raman spectroscopy. The chains within crystalline phase began to orient toward the stretching direction beyond the yielding region and the orientation behavior was not affected by the strain rate. While the stretching stress along the crystalline chains was also not affected by the strain rate, the peak shifts of the Raman bands at 1130, 1418, 1440 and 1460 cm-1, which are sensitive to the interchain interactions obviously, depended on the strain rate; the higher strain rates lead to the stronger stretching stress or negative pressure on the crystalline and amorphous chains. These effects of the strain rate on the microscopic deformation was associated with the cavitation and the void formation leading to the release of the internal pressure.

  17. Optofluidic time-stretch quantitative phase microscopy.

    Science.gov (United States)

    Guo, Baoshan; Lei, Cheng; Wu, Yi; Kobayashi, Hirofumi; Ito, Takuro; Yalikun, Yaxiaer; Lee, Sangwook; Isozaki, Akihiro; Li, Ming; Jiang, Yiyue; Yasumoto, Atsushi; Di Carlo, Dino; Tanaka, Yo; Yatomi, Yutaka; Ozeki, Yasuyuki; Goda, Keisuke

    2018-03-01

    Innovations in optical microscopy have opened new windows onto scientific research, industrial quality control, and medical practice over the last few decades. One of such innovations is optofluidic time-stretch quantitative phase microscopy - an emerging method for high-throughput quantitative phase imaging that builds on the interference between temporally stretched signal and reference pulses by using dispersive properties of light in both spatial and temporal domains in an interferometric configuration on a microfluidic platform. It achieves the continuous acquisition of both intensity and phase images with a high throughput of more than 10,000 particles or cells per second by overcoming speed limitations that exist in conventional quantitative phase imaging methods. Applications enabled by such capabilities are versatile and include characterization of cancer cells and microalgal cultures. In this paper, we review the principles and applications of optofluidic time-stretch quantitative phase microscopy and discuss its future perspective. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Summary of the stretching tectonics research

    International Nuclear Information System (INIS)

    Yu Dagan

    1994-01-01

    The rise of stretching tectonics is established on the basis of recent structural geology theory, the establishment of metamorphic nucleus complex structural model on one hand plays an important promoting art to the development of stretching structure, on the other hand, it needs constant supplement and perfection in practice. Metamorphic nucleus complex is the carrier of comparatively deep geological information in vertical section of the crust and has wide distribution in the era of south China. Evidently, it can be taken as the 'key' to understanding the deep and studying the basement, Strengthening the study will play the important promoting role to the deep prospecting. The study of stretching tectonics is not only limited within the range of structure and metamorphism, but combine with the studies of sedimentation, magmatism, metamorphism and mineralization, thus form a new field of tectonic geology of self-developing system

  19. Lattice stretching bistability and dynamic heterogeneity

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Savin, A. V.; Zolotaryuk, A. V.

    2012-01-01

    A simple one-dimensional lattice model is suggested to describe the experimentally observed plateau in force-stretching diagrams for some macromolecules. This chain model involves the nearest-neighbor interaction of a Morse-like potential (required to have a saturation branch) and a harmonic second......-neighbor coupling. Under an external stretching applied to the chain ends, the intersite Morse-like potential results in the appearance of a double-well potential within each chain monomer, whereas the interaction between the second neighbors provides a homogeneous bistable (degenerate) ground state, at least...... stretched bonds with a double-well potential. This case allows us to explain the existence of a plateau in the force-extension diagram for DNA and α-helix protein. Finally, the soliton dynamics are studied in detail....

  20. Optofluidic time-stretch microscopy: recent advances

    Science.gov (United States)

    Lei, Cheng; Nitta, Nao; Ozeki, Yasuyuki; Goda, Keisuke

    2018-04-01

    Flow cytometry is an indispensable method for valuable applications in numerous fields such as immunology, pathology, pharmacology, molecular biology, and marine biology. Optofluidic time-stretch microscopy is superior to conventional flow cytometry methods for its capability to acquire high-quality images of single cells at a high-throughput exceeding 10,000 cells per second. This makes it possible to extract copious information from cellular images for accurate cell detection and analysis with the assistance of machine learning. Optofluidic time-stretch microscopy has proven its effectivity in various applications, including microalga-based biofuel production, evaluation of thrombotic disorders, as well as drug screening and discovery. In this review, we discuss the principles and recent advances of optofluidic time-stretch microscopy.

  1. Deep neural networks show an equivalent and often superior performance to dermatologists in onychomycosis diagnosis: Automatic construction of onychomycosis datasets by region-based convolutional deep neural network.

    Directory of Open Access Journals (Sweden)

    Seung Seog Han

    Full Text Available Although there have been reports of the successful diagnosis of skin disorders using deep learning, unrealistically large clinical image datasets are required for artificial intelligence (AI training. We created datasets of standardized nail images using a region-based convolutional neural network (R-CNN trained to distinguish the nail from the background. We used R-CNN to generate training datasets of 49,567 images, which we then used to fine-tune the ResNet-152 and VGG-19 models. The validation datasets comprised 100 and 194 images from Inje University (B1 and B2 datasets, respectively, 125 images from Hallym University (C dataset, and 939 images from Seoul National University (D dataset. The AI (ensemble model; ResNet-152 + VGG-19 + feedforward neural networks results showed test sensitivity/specificity/ area under the curve values of (96.0 / 94.7 / 0.98, (82.7 / 96.7 / 0.95, (92.3 / 79.3 / 0.93, (87.7 / 69.3 / 0.82 for the B1, B2, C, and D datasets. With a combination of the B1 and C datasets, the AI Youden index was significantly (p = 0.01 higher than that of 42 dermatologists doing the same assessment manually. For B1+C and B2+ D dataset combinations, almost none of the dermatologists performed as well as the AI. By training with a dataset comprising 49,567 images, we achieved a diagnostic accuracy for onychomycosis using deep learning that was superior to that of most of the dermatologists who participated in this study.

  2. Deep neural networks show an equivalent and often superior performance to dermatologists in onychomycosis diagnosis: Automatic construction of onychomycosis datasets by region-based convolutional deep neural network.

    Science.gov (United States)

    Han, Seung Seog; Park, Gyeong Hun; Lim, Woohyung; Kim, Myoung Shin; Na, Jung Im; Park, Ilwoo; Chang, Sung Eun

    2018-01-01

    Although there have been reports of the successful diagnosis of skin disorders using deep learning, unrealistically large clinical image datasets are required for artificial intelligence (AI) training. We created datasets of standardized nail images using a region-based convolutional neural network (R-CNN) trained to distinguish the nail from the background. We used R-CNN to generate training datasets of 49,567 images, which we then used to fine-tune the ResNet-152 and VGG-19 models. The validation datasets comprised 100 and 194 images from Inje University (B1 and B2 datasets, respectively), 125 images from Hallym University (C dataset), and 939 images from Seoul National University (D dataset). The AI (ensemble model; ResNet-152 + VGG-19 + feedforward neural networks) results showed test sensitivity/specificity/ area under the curve values of (96.0 / 94.7 / 0.98), (82.7 / 96.7 / 0.95), (92.3 / 79.3 / 0.93), (87.7 / 69.3 / 0.82) for the B1, B2, C, and D datasets. With a combination of the B1 and C datasets, the AI Youden index was significantly (p = 0.01) higher than that of 42 dermatologists doing the same assessment manually. For B1+C and B2+ D dataset combinations, almost none of the dermatologists performed as well as the AI. By training with a dataset comprising 49,567 images, we achieved a diagnostic accuracy for onychomycosis using deep learning that was superior to that of most of the dermatologists who participated in this study.

  3. Stretching and folding mechanism in foams

    International Nuclear Information System (INIS)

    Tufaile, Alberto; Pedrosa Biscaia Tufaile, Adriana

    2008-01-01

    We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board

  4. Filament stretching rheometer: inertia compensation revisited

    DEFF Research Database (Denmark)

    Szabo, Peter; McKinley, Gareth H.

    2003-01-01

    The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end of the e......The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end...

  5. Stretching and folding mechanism in foams

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

    2008-10-13

    We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

  6. A comparison of two stretching programs for hamstring muscles: A randomized controlled assessor-blinded study.

    Science.gov (United States)

    Demoulin, Christophe; Wolfs, Sébastien; Chevalier, Madeline; Granado, Caroline; Grosdent, Stéphanie; Depas, Yannick; Roussel, Nathalie; Hage, Renaud; Vanderthommen, Marc

    2016-01-01

    Most parameters regarding hamstring flexibility training programs have been investigated; however, the joint (i.e. hip or knee) on which the stretching should preferentially be focused needs to be further explored. This randomized controlled assessor-blinded study aimed to investigate the influence of this parameter. We randomly assigned 111 asymptomatic participants with tight hamstring muscles in three groups: a control group and two groups following a different home-based 8-week (five 10-minute sessions per week) hamstring stretching program (i.e. stretching performed by flexing the hip while keeping the knee extended [SH] or by first flexing the hip with a flexed knee and then extending the knee [SK]). Range of motion (ROM) of hip flexion and knee extension were measured before and after the stretching program by means of the straight leg raising test and the passive knee extension angle test, respectively. Eighty-nine participants completed the study. A significant increase in ROM was observed at post-test. Analyses showed significant group-by-time interactions for changes regarding all outcomes. Whereas the increase in hip flexion and knee extension ROM was higher in the stretching groups than in the CG (especially for the SH group p 0.05). In conclusion, the fact that both stretching programs resulted in similar results suggests no influence of the joint at which the stretching is focused upon, as assessed by the straight leg raising and knee extension angle tests.

  7. Eliminating electromechanical instability in dielectric elastomers by employing pre-stretch

    International Nuclear Information System (INIS)

    Jiang, Liang; Jerrams, Stephen; Betts, Anthony; Kennedy, David

    2016-01-01

    Electromechanical instability (EMI) is one of most common failure modes for dielectric elastomers (DEs). It has been reported that pre-stretching a DE sample can suppress EMI due to strain stiffening taking place for larger strains and a higher elastic modulus are achieved at high stretch ratios when a voltage is applied to the material. In this work, the influence of equi-biaxial stretch on DE secant modulus was studied using VHB 4910 and silicone rubber (SR) composites containing barium titanate (BaTiO 3 , BT) particles and also dopamine coated BT (DP-BT) particles. The investigation of equi-biaxial deformation and EMI failure for VHB 4910 was undertaken by introducing a voltage-stretch function. The results showed that EMI was suppressed by equi-biaxial pre-stretch for all the DEs fabricated and tested. The stiffening properties of the DE materials were also studied with respect to the secant modulus. Furthermore, a voltage-induced strain of above 200% was achieved for the polyacrylate film by applying a pre-stretch ratio of 2.0 without EMI occurring. However, a maximum voltage-induced strain in the polyacrylate film of 78% was obtained by the SR/20 wt% DP-BT composite for a lower applied pre-stretch ratio of 1.6 and again EMI was eliminated. (paper)

  8. The Comparative Study of the Effect of Stabilization Exercise and Stretching-Strengthening Exercise on Balance Parameters in Forward Head Posture Patients

    Directory of Open Access Journals (Sweden)

    Solmaz Salehi

    2013-04-01

    Full Text Available Objective: Balance disturbance is one of the observed impairments in patient with forward head posture (FHP. The aim of this study was comparing the effect of stabilization and stretching-strengthening exercises on the improvement of balance in these patients. Materials & Methods: Thirty three females with FHP were randomized into three groups of stabilization training, stretching-strengthening and control. The degree of FHP was measured using plumb line and the crania-vertebral angle. Balance tests performed in three different standing conditions on a force platform. The subjects were evaluated after 6 weeks training and 1 month follow-up by repeated measure ANOVA and T-test through SPSS software. Results: Balance parameters in both stretching-strengthening and control groups showed no significant changes (P>0.05 while in the stabilization group, significant decrease in displacement and velocity of center of pressure were seen under conditions of double-leg, eyes-open, foam-surface and single-leg, eyes-closed, rigid-surface (P0.05. Conclusion: In the conditions of standing that visual and proprioception information from plantar region of foot is challenged, stabilization exercises lead to more balance improvement than stretching-strengthening exercises.

  9. Structural Transitions in Supercoiled Stretched DNA

    Science.gov (United States)

    v, Croquette

    1998-03-01

    Using magnetic micromanipulation techniques [Strick 96]( uc(T.R.) Strick, J.-F. Allemand, D. Bensimon, A. Bensimon) and uc(V.) Croquette, "The elasticity of a single supercoiled DNA molecule", Science, 271, 1835 (1996)., we have studied the mechanical properties (force versus extension) of single DNA molecules under a wide range of torsional stresses (supercoiling). We show that unwinding the DNA double helix leads to a phase separation between regular B-DNA and denaturation bubbles. The fraction of denatured molecule increases linearly with the degree of unwinding, beginning at a value of 1% unwinding. We have confirmed this denatured state by hybridization of homologous single-stranded DNA probes and by a chemical attack of the exposed bases. Surprisingly, when we overwind the molecule, the elasticity curves we obtain may also be interpreted by the coexistence of two phases, B-DNA and a new phase which we note P-DNA. The fraction of this new phase increases smoothly with overwinding, beginning at 3 % and continuing up to 300 %. Our results indicate that this new phase is four times more twisted that the standard B-DNA and is 1.75 times longer. Although the structure of this phase is not yet known, such a high twisting can only be attained if the sugar-phosphate backbones of the two strands are twisted closely while the bases are expelled outside of the molecule's core, in a structure reminiscent of the one proposed by Pauling. Indeed we have shown that this new phase is sensitive to chemical attack whereas the B-DNA is not. This new phase begins to appear on a molecule overwound by 3 % and stretched by a force of 5 pN, conditions typically encountered in vivo during gene transcription. This new phase may thus play a biological role (for more details).

  10. Acute Effect of Different Combined Stretching Methods on Acceleration and Speed in Soccer Players

    Directory of Open Access Journals (Sweden)

    Amiri-Khorasani Mohammadtaghi

    2016-04-01

    Full Text Available The purpose of this study was to investigate the acute effect of different stretching methods, during a warm-up, on the acceleration and speed of soccer players. The acceleration performance of 20 collegiate soccer players (body height: 177.25 ± 5.31 cm; body mass: 65.10 ± 5.62 kg; age: 16.85 ± 0.87 years; BMI: 20.70 ± 5.54; experience: 8.46 ± 1.49 years was evaluated after different warm-up procedures, using 10 and 20 m tests. Subjects performed five types of a warm-up: static, dynamic, combined static + dynamic, combined dynamic + static, and no-stretching. Subjects were divided into five groups. Each group performed five different warm-up protocols in five non-consecutive days. The warm-up protocol used for each group was randomly assigned. The protocols consisted of 4 min jogging, a 1 min stretching program (except for the no-stretching protocol, and 2 min rest periods, followed by the 10 and 20 m sprint test, on the same day. The current findings showed significant differences in the 10 and 20 m tests after dynamic stretching compared with static, combined, and no-stretching protocols. There were also significant differences between the combined stretching compared with static and no-stretching protocols. We concluded that soccer players performed better with respect to acceleration and speed, after dynamic and combined stretching, as they were able to produce more force for a faster execution.

  11. The acute effects of stretching with vibration on dynamic flexibility in young female gymnasts.

    Science.gov (United States)

    Johnson, Aaron W; Warcup, Caisa N; Seeley, Matthew K; Eggett, Dennis; Feland, Jeffery B

    2018-01-10

    While stretching with vibration has been shown to improve static flexibility; the effect of stretching with vibration on dynamic flexibility is not well known. The purpose of this study was to examine the effectiveness of stretching with vibration on acute dynamic flexibility and jump height in novice and advanced competitive female gymnasts during a split jump. Female gymnast (n=27, age: 11.5 ± 1.7 years, Junior Olympic levels 5-10) participated in this cross-over study. Dynamic flexibility during gymnastic split jumps were video recorded and analyzed with Dartfish software. All participants completed both randomized stretching protocols with either the vibration platform turned on (VIB) (frequency of 30 Hz and 2 mm amplitude) or off (NoVIB) separated by 48 h. Participants performed 4 sets of three stretches on the vibration platform. Each stretch was held for 30 s with 5 s rest for a total of 7 min of stretch. Split jump flexibility decreased significantly from pre to post measurement in both VIB (-5.8°±5.9°) (p<0.001) and NoVIB (-2.6°±6.1°) (p=0.041) conditions (adjusted for gymnast level). This effect was greatest in lower skill level gymnasts (p=0.003), while the highest skill level gymnasts showed no significant decrease in the split jump (p=0.105). Jump height was not significantly different between conditions (p=0.892) or within groups (p=0.880). An acute session of static stretching with or without vibration immediately before performance does not alter jump height. Stretching with vibration immediately prior to gymnastics competition decreases split jump flexibility in lower level gymnasts more than upper level gymnasts.

  12. The passive hamstring stretch test: clinical evaluation.

    Science.gov (United States)

    Fisk, J W

    1979-03-28

    The passive hamstring stretch test is described. Using a modified goniometer it is shown that independent measurements taken by trained examiners approximate very closely to each other. This establishes the test as a valid objective measurement. The possible value of this test as a research tool in low back pain problems is discussed.

  13. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  14. Stretched exponential distributions in Nature and Economy: ``Fat tails'' with characteristic scales

    OpenAIRE

    Laherrère, Jean; Sornette, D.

    1998-01-01

    To account quantitatively for many reported ``natural'' fat tail distributions in Nature and Economy, we propose the stretched exponential family as a complement to the often used power law distributions. It has many advantages, among which to be economical with only two adjustable parameters with clear physical interpretation. Furthermore, it derives from a simple and generic mechanism in terms of multiplicative processes. We show that stretched exponentials describe very well the distributi...

  15. Stretching single fibrin fibers hampers their lysis.

    Science.gov (United States)

    Li, Wei; Lucioni, Tomas; Li, Rongzhong; Bonin, Keith; Cho, Samuel S; Guthold, Martin

    2017-09-15

    Blood clots, whose main structural component is a mesh of microscopic fibrin fibers, experience mechanical strain from blood flow, clot retraction and interactions with platelets and other cells. We developed a transparent, striated and highly stretchable substrate made from fugitive glue (a styrenic block copolymer) to investigate how mechanical strain affects lysis of single, suspended fibrin fibers. In this suspended fiber assay, lysis manifested itself by fiber elongation, thickening (disassembly), fraying and collapse. Stretching single fibrin fibers significantly hampered their lysis. This effect was seen in uncrosslinked and crosslinked fibers. Crosslinking (without stretching) also hampered single fiber lysis. Our data suggest that strain is a novel mechanosensitive factor that regulates blood clot dissolution (fibrinolysis) at the single fiber level. At the molecular level of single fibrin molecules, strain may distort, or hinder access to, plasmin cleavage sites and thereby hamper lysis. Fibrin fibers are the major structural component of a blood clot. We developed a highly stretchable substrate made from fugitive glue and a suspended fibrin fiber lysis assay to investigate the effect of stretching on single fibrin fibers lysis. The key findings from our experiments are: 1) Fibers thicken and elongate upon lysis; 2) stretching strongly reduces lysis; 3) this effect is more pronounced for uncrosslinked fibers; and 4) stretching fibers has a similar effect on reducing lysis as crosslinking fibers. At the molecular level, strain may distort plasmin cleavage sites, or restrict access to those sites. Our results suggest that strain may be a novel mechanobiological factor that regulates fibrinolysis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. A zinc, copper and citric acid biocomplex shows promise for control of Xylella fastidiosa subsp. pauca in olive trees in Apulia region (southern Italy)

    Science.gov (United States)

    The bacterium Xylella fastidiosa subsp. pauca is associated with the “olive quick decline syndrome” in the Apulia region of southern Italy. To investigate control of this phytopathogen, a compound containing zinc and copper complexed with citric-acid hydracids (Dentamet®) was evaluated for in vitro ...

  17. The static actuation of dielectric elastomer actuators: how does pre-stretch improve actuation?

    International Nuclear Information System (INIS)

    Kofod, Guggi

    2008-01-01

    It has previously been shown that providing dielectric elastomer actuators with a level of pre-stretch can improve properties such as breakdown strength, actuation strain and efficiency. The actuation in such actuators depends on an interplay between the highly nonlinear hyperelastic stress-strain behaviour with the electrostatic Maxwell's stress; however, the direct effects of pre-stretch on the electromechanical coupling have still not been investigated in detail. We compare several experimental results found in the literature on the hyperelastic parameters of the Ogden model for the commonly used material VHB 4910, and introduce a more detailed and thus more accurate fit to a previous uniaxial stress-strain experiment. Electrostatic actuation models for a pure shear cuboid dielectric elastomer actuator with pre-stretch are introduced, for both intensive and extensive variables. For both intensive and extensive variables the constant strain (blocked stress or force) as well as the actuation strain is presented. It is shown how in the particular case of isotropic amorphous elastomers the pre-stretch does not affect the electromechanical coupling directly, and that the enhancement in actuation strain due to pre-stretch occurs through the alteration of the geometrical dimensions of the actuator. Also, the presence of the optimum load is explained as being due to the plateau region in the force-stretch curve, and it is shown that pre-stretch is not able to affect its position. Finally, it is shown how the simplified Ogden fit leads to entirely different conclusions for actuation strain in terms of extensive variables as does the detailed fit, emphasizing the importance of employing accurate hyperelastic models for the stress-stretch behaviour of the elastomer.

  18. How to determine local stretching and tension in a flow-stretched DNA molecule

    DEFF Research Database (Denmark)

    Pedersen, Jonas Nyvold; Marie, Rodolphe; Kristensen, Anders

    2016-01-01

    We determine the nonuniform stretching of and tension in amega base pairs-long fragment of deoxyribonucleic acid (DNA) that is flow stretched in a nanofluidic chip. We use no markers, do not know the contour length of the DNA, and do not have the full DNA molecule inside our field of view. Instead......, we analyze the transverse thermal motion of the DNA. Tension at the center of the DNA adds up to 16 pN, giving almost fully stretched DNA. This method was devised for optical mapping of DNA, specifically, DNA denaturation patterns. It may be useful also for other studies, e.g., DNA......-protein interactions, specifically, their tension dependence. Generally, wherever long strands of DNA—e.g., native DNA extracted from human cells or bacteria—must be stretched with ease for inspection, this method applies....

  19. Origin of the blue shift of the CH stretching band for 2-butoxyethanol in water.

    Science.gov (United States)

    Katsumoto, Yukiteru; Komatsu, Hiroyuki; Ohno, Keiichi

    2006-07-26

    The blue shift of the isolated CD stretching band of 2-butoxyethanol (C4E1), which is observed for the aqueous solution during the dilution process, has been investigated by infrared (IR) spectroscopy and quantum chemical calculations. Mono-deuterium-labeled C4E1's were employed to remove the severe overlapping among the CH stretching bands. The isolated CD stretching mode of the alpha-methylene in the butoxy group shows a large blue shift, while those of the beta-methylene and methyl groups are not largely shifted. The spectral simulation results for the C4E1/H2O complexes indicate that the large blue shift of the CD stretching band of the butoxy group arises mainly from the hydration of the ether oxygen atom.

  20. Effectiveness of passive stretching versus hold relax technique in flexibility of hamstring muscle

    Directory of Open Access Journals (Sweden)

    Gauri Shankar

    2010-10-01

    Full Text Available Aim: To compare the effectiveness of passive stretching and hold relax technique in the flexibility of hamstring muscle. Methods: A total of 80 normal healthy female subjects between age group 20-30 years referred to the department of physiotherapy, Sumandeep Vidyapeeth University, sampling method being convenient sampling. The subjects were randomly divided in two groups i.e. passive stretching group (n=40 and PNF group (n=40 and given passive stretching and proprioceptive neuromuscular facilitation technique respectively. Active knee extension range was measured before and after the intervention by goniometer. Results: t test showed a highly significant (p=0.000 increase in range of motion in PNF group. Conclusion: Proprioceptive neuromuscular facilitation technique is more effective in increasing hamstring flexibility than the passive stretching.

  1. EFFECTIVENESS OF PNF STRETCHING AND CYCLIC STRETCHING OF CALF TIGHTNESS ON COLLEGE GOING GIRLS

    Directory of Open Access Journals (Sweden)

    Ashlesha Sirari

    2015-06-01

    Full Text Available Background: Flexibility helps with injury prevention, the reduction of soreness following a workout, and a general sense of well-being. There are different stretching techniques and protocols for improvements in calf extensibility and flexibility. The purpose of the study was to investigate the effectiveness of two techniques i.e. CYCLIC and PNF stretching which improves calf flexibility. This study was done to find the effectiveness of calf Cyclic and PNF stretching technique to improve calf flexibility. Methods: 30 subjects with age group 21-22 years were randomly allocated to 2 groups equally. Group 1(n=15 were given CYCLIC and group 2(n=15 were given PNF stretching technique. Plantar flexion was used to measure the calf tightness which was done before and after the treatment. Treatment was given for 7 days and on the 7th day the calf tightness was again measured. Results: The mean difference of the CYCLIC is 4.6 and mean difference of PNF is 4.7 which indicate that CYCLIC and PNF both are effective to improve calf flexibility but PNF is more effective than CYCLIC to improve calf flexibility. Conclusion: The neurophysiological basis of PNF, stating that the excitatory efficient of the neuromuscular spindle or the inhibitory afferent of the Golgi tendon organ (GTO or both are responsible for the effects. During PNF stretch and isometric contraction of stretched agonists for extended period may cause activation of its neuromuscular spindle. The increase in tension created during the isometric contraction of the pre – lengthened agonist contracts concentrically. Both the fascia & the spindle of the agonist adjust to the nearly lengthened position. These impulses travel via causing post synaptic inhibition of the motor neuron to agonist increasing the tension from the GTO. These impulses can override the impulses coming from the neuromuscular spindles arousing the muscle to reflexly resist to the change in length, thus helping in lengthening

  2. Flexibility and stretching physiology : responses and adaptations to different stretching intensities.

    OpenAIRE

    Freitas, Sandro Remo Martins Neves Ramos

    2014-01-01

    Doutoramento em Motricidade Humana, especialidade de Biomecânica Research and reported literature regarding the conceptual, methodological, and training effects of stretching with different intensities are scarce. The purposes of this thesis were to: i) explore and develop methodological conditions to achieve the second purpose (studies: 1 to 3); ii) characterize the acute and chronic effects induced by different stretching intensities on skeletal muscle and joint mechanical properti...

  3. A thirty year, fine-scale, characterization of area burned in Canadian forests shows evidence of regionally increasing trends in the last decade.

    Science.gov (United States)

    Coops, Nicholas C; Hermosilla, Txomin; Wulder, Michael A; White, Joanne C; Bolton, Douglas K

    2018-01-01

    Fire as a dominant disturbance has profound implications on the terrestrial carbon cycle. We present the first ever multi-decadal, spatially-explicit, 30 meter assessment of fire regimes across the forested ecoregions of Canada at an annual time-step. From 1985 to 2015, 51 Mha burned, impacting over 6.5% of forested ecosystems. Mean annual area burned was 1,651,818 ha and varied markedly (σ = 1,116,119), with 25% of the total area burned occurring in three years: 1989, 1995, and 2015. Boreal forest types contained 98% of the total area burned, with the conifer-dominated Boreal Shield containing one-third of all burned area. While results confirm no significant national trend in burned area for the period of 1985 to 2015, a significant national increasing trend (α = 0.05) of 11% per year was evident for the past decade (2006 to 2015). Regionally, a significant increasing trend in total burned area from 1985 to 2015 was observed in the Montane Cordillera (2.4% increase per year), while the Taiga Plains and Taiga Shield West displayed significant increasing trends from 2006 to 2015 (26.1% and 12.7% increases per year, respectively). The Atlantic Maritime, which had the lowest burned area of all ecozones (0.01% burned per year), was the only ecozone to display a significant negative trend (2.4% decrease per year) from 1985 to 2015. Given the century-long fire return intervals in many of these ecozones, and large annual variability in burned area, short-term trends need to be interpreted with caution. Additional interpretive cautions are related to year used for trend initiation and the nature and extents of spatial regionalizations used for summarizing findings. The results of our analysis provide a baseline for monitoring future national and regional trends in burned area and offer spatially and temporally detailed insights to inform science, policy, and management.

  4. Investigation of the 5' flanking region and exon 3 polymorphisms of IGF-1 gene showed moderate association with semen quality in Sanjabi breed rams.

    Science.gov (United States)

    Bakhtiar, R; Abdolmohammadi, A; Hajarian, H; Nikousefat, Z; Kalantar-Neyestanaki, D

    2017-12-01

    In this study, semen samples were collected from 96 Sanjabi rams in order to investigate the IGF-1 gene polymorphisms and their relationship with the characteristics of semen quality and testicular size. The dimensions of scrotal length, width and circumference were measured during autumn and spring over two years. Blood samples were simultaneously collected from jugular vein to extract DNA. PCR was performed using specific primers to amplify 294 and 272bp fragments including 5' regulatory region and exon 3 of IGF-1 gene, respectively. PCR products were digested by BFOI and Eco88l restriction enzymes, respectively. Two genotypes including AA (194 and 100bp), AB (294, 194 and 100bp) and all possible genotypes including CC (182 and 90bp), CT (272, 182, and 90bp) and TT (272bp) were observed for 5' flanking region and exon 3 of IGF-1 gene, respectively. The significant differences among IGF-1 genotypes for testicular dimensions were not observed. However, the polymorphism of 5' flanking region in the studied population had significant effect on individual motility and percent morphology traits. Animals with AB genotype had significantly higher individual motility compared with AA genotype (P IGF-1 gene had significant effect on individual motility, concentration, morphology and water test traits. Animals with CT genotype had the highest sperm concentration (P IGF-1 genotypes. It might be concluded that polymorphisms in IGF-1gene can be considered to develop male fertility in future and for using in selection process of better animals under masker assisted selection programs. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The influence of stretching on tensile strength and solubility of poly(vinyl alcohol) fibres

    NARCIS (Netherlands)

    Heikens, D.; Bleijenberg, A.C.A.M.; Hoppenbrouwers, J.J.M.; Barentsen, W.M.

    1971-01-01

    The strength of wet-spun poly(vinyl alcohol) (pva) fibres is given as function of bath-stretching, wet-stretching and hot-stretching. In the two equations derived for strength of wet-stretching and hot-stretching the complex influence of the bath-stretching and hot-stretching is demonstrated. The

  6. Stretch strength of Al-Li alloy sheet

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Sawa, Y.; Yokoyama, T.; Fujimoto, S. [Science Univ. of Tokyo (Japan). Dept. of Mech. Eng.; Sakamoto, T. [Kobe Steel Works, Tokyo (Japan)

    1998-07-01

    Stretch test on Al-Li alloy sheet was carried out in stretch rate of 0.01 to 0.2 mm/sec. The limiting stretch depth was measured in various conditions and the following results were obtained. (1) Stretch rate does not affect the limiting stretch depth of Al-Li alloy. (2) The limiting stretch depth is increased with increase of the profile radius. (3) Strain hardening exponent(n-value) and r-value of Lankford do not affect the limiting stretch depth. (4) Rapture pattern in stretch test of Al is {alpha} type rapture and that of Al-Li alloy is straight line type rapture. (orig.) 4 refs.

  7. String Stretching, Frequency Modulation, and Banjo Clang

    OpenAIRE

    Politzer, David

    2014-01-01

    The banjo’s floating bridge, string break angle, and flexible drumhead all contribute to substantial audio range frequency modulation. From the world of electronic music synthesis, it is known that modulating higher frequency sounds with lower acoustic frequencies leads to metallic and bell-like tone. The mechanics of the banjo does just that quite naturally, modulating fundamentals and harmonics with the motion of the bridge. In technical terms, with a floating bridge, string stretching is f...

  8. The stretch zone of automotive steel sheets

    Indian Academy of Sciences (India)

    The stretch zone of automotive steel sheets. L' AMBRIŠKO1,∗ and L PEŠEK2. 1Institute of Structural Engineering, Faculty of Civil Engineering,. Technical University of Košice, Vysokoškolská 4, 042 00 Košice, Slovak Republic. 2Department of Materials Science, Faculty of Metallurgy,. Technical University of Košice, Letná 9, ...

  9. Spontaneous bending of pre-stretched bilayers.

    Science.gov (United States)

    DeSimone, Antonio

    2018-01-01

    We discuss spontaneously bent configurations of pre-stretched bilayer sheets that can be obtained by tuning the pre-stretches in the two layers. The two-dimensional nonlinear plate model we use for this purpose is an adaptation of the one recently obtained for thin sheets of nematic elastomers, by means of a rigorous dimensional reduction argument based on the theory of Gamma-convergence (Agostiniani and DeSimone in Meccanica. doi:10.1007/s11012-017-0630-4, 2017, Math Mech Solids. doi:10.1177/1081286517699991, arXiv:1509.07003, 2017). We argue that pre-stretched bilayer sheets provide us with an interesting model system to study shape programming and morphing of surfaces in other, more complex systems, where spontaneous deformations are induced by swelling due to the absorption of a liquid, phase transformations, thermal or electro-magnetic stimuli. These include bio-mimetic structures inspired by biological systems from both the plant and the animal kingdoms.

  10. Dynamics and structure of stretched flames

    Energy Technology Data Exchange (ETDEWEB)

    Law, C.K. [Princeton Univ., NJ (United States)

    1993-12-01

    This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

  11. Drop dynamics on a stretched viscoelastic filament: An experimental study

    Science.gov (United States)

    Peixinho, Jorge; Renoult, Marie-Charlotte; Crumeyrolle, Olivier; Mutabazi, Innocent

    2016-11-01

    Capillary pressure can destabilize a thin liquid filament during breakup into a succession of drops. Besides, the addition of a linear, high molecular weight, flexible and soluble polymer is enough to modify the morphology of this instability. In the time period preceding the breakup, the development of beads-on-a-string structures where drops are connected by thin threads is monitored. The drops dynamics involve drop formation, drop migration and drop coalescence. Experiments using a high-speed camera on stretched bridges of viscoelastic polymeric solutions were conducted for a range of viscosities and polymer concentrations. The rheological properties of the solutions are also quantified through conventional shear rheology and normal stress difference. The overall goal of this experimental investigation is to gain more insight into the formation and time evolution of the drops. The project BIOENGINE is co-financed by the European Union with the European regional development fund and by the Normandie Regional Council.

  12. Hyperglycemia Augments the Adipogenic Transdifferentiation Potential of Tenocytes and Is Alleviated by Cyclic Mechanical Stretch.

    Science.gov (United States)

    Wu, Yu-Fu; Huang, Yu-Ting; Wang, Hsing-Kuo; Yao, Chung-Chen Jane; Sun, Jui-Sheng; Chao, Yuan-Hung

    2017-12-28

    Diabetes mellitus is associated with damage to tendons, which may result from cellular dysfunction in response to a hyperglycemic environment. Tenocytes express diminished levels of tendon-associated genes under hyperglycemic conditions. In contrast, mechanical stretch enhances tenogenic differentiation. However, whether hyperglycemia increases the non-tenogenic differentiation potential of tenocytes and whether this can be mitigated by mechanical stretch remains elusive. We explored the in vitro effects of high glucose and mechanical stretch on rat primary tenocytes. Specifically, non-tenogenic gene expression, adipogenic potential, cell migration rate, filamentous actin expression, and the activation of signaling pathways were analyzed in tenocytes treated with high glucose, followed by the presence or absence of mechanical stretch. We analyzed tenocyte phenotype in vivo by immunohistochemistry using an STZ (streptozotocin)-induced long-term diabetic mouse model. High glucose-treated tenocytes expressed higher levels of the adipogenic transcription factors PPAR γ and C/EBPs. PPARγ was also highly expressed in diabetic tendons. In addition, increased adipogenic differentiation and decreased cell migration induced by high glucose implicated a fibroblast-to-adipocyte phenotypic change. By applying mechanical stretch to tenocytes in high-glucose conditions, adipogenic differentiation was repressed, while cell motility was enhanced, and fibroblastic morphology and gene expression profiles were strengthened. In part, these effects resulted from a stretch-induced activation of ERK (extracellular signal-regulated kinases) and a concomitant inactivation of Akt. Our results show that mechanical stretch alleviates the augmented adipogenic transdifferentiation potential of high glucose-treated tenocytes and helps maintain their fibroblastic characteristics. The alterations induced by high glucose highlight possible pathological mechanisms for diabetic tendinopathy

  13. Effects of acute static, ballistic, and PNF stretching exercise on the muscle and tendon tissue properties.

    Science.gov (United States)

    Konrad, A; Stafilidis, S; Tilp, M

    2017-10-01

    The purpose of this study was to investigate the influence of a single static, ballistic, or proprioceptive neuromuscular facilitation (PNF) stretching exercise on the various muscle-tendon parameters of the lower leg and to detect possible differences in the effects between the methods. Volunteers (n = 122) were randomly divided into static, ballistic, and PNF stretching groups and a control group. Before and after the 4 × 30 s stretching intervention, we determined the maximum dorsiflexion range of motion (RoM) with the corresponding fascicle length and pennation angle of the gastrocnemius medialis. Passive resistive torque (PRT) and maximum voluntary contraction (MVC) were measured with a dynamometer. Observation of muscle-tendon junction (MTJ) displacement with ultrasound allowed us to determine the length changes in the tendon and muscle, respectively, and hence to calculate stiffness. Although RoM increased (static: +4.3%, ballistic: +4.5%, PNF: +3.5%), PRT (static: -11.4%, ballistic: -11.5%, PNF: -13,7%), muscle stiffness (static: -13.1%, ballistic: -20.3%, PNF: -20.2%), and muscle-tendon stiffness (static: -11.3%, ballistic: -10.5%, PNF: -13.7%) decreased significantly in all the stretching groups. Only in the PNF stretching group, the pennation angle in the stretched position (-4.2%) and plantar flexor MVC (-4.6%) decreased significantly. Multivariate analysis showed no clinically relevant difference between the stretching groups. The increase in RoM and the decrease in PRT and muscle-tendon stiffness could be explained by more compliant muscle tissue following a single static, ballistic, or PNF stretching exercise. © 2017 The Authors Scandinavian Journal of Medicine & Science In Sports Published by John Wiley & Sons Ltd.

  14. Mechanical stretch induces MMP-2 release and activation in lung endothelium: role of EMMPRIN.

    Science.gov (United States)

    Haseneen, Nadia A; Vaday, Gayle G; Zucker, Stanley; Foda, Hussein D

    2003-03-01

    High-volume mechanical ventilation leads to ventilator-induced lung injury. This type of lung injury is accompanied by an increased release and activation of matrix metalloproteinases (MMPs). To investigate the mechanism leading to the increased MMP release, we systematically studied the effect of mechanical stretch on human microvascular endothelial cells isolated from the lung. We exposed cells grown on collagen 1 BioFlex plates to sinusoidal cyclic stretch at 0.5 Hz using the Flexercell system with 17-18% elongation of cells. After 4 days of cell stretching, conditioned media and cell lysate were collected and analyzed by gelatin, casein, and reverse zymograms as well as Western blotting. RT-PCR of mRNA extracted from stretched cells was performed. Our results show that 1) cyclic stretch led to increased release and activation of MMP-2 and MMP-1; 2) the activation of MMP-2 was accompanied by an increase in membrane type-1 MMP (MT1-MMP) and inhibited by a hydroxamic acid-derived inhibitor of MMPs (Prinomastat, AG3340); and 3) the MMP-2 release and activation were preceded by an increase in production of extracellular MMP inducer (EMMPRIN). These results suggest that cyclic mechanical stretch leads to MMP-2 activation through an MT1-MMP mechanism. EMMPRIN may play an important role in the release and activation of MMPs during lung injury.

  15. Process Parameter Identification in Thin Film Flows Driven by a Stretching Surface

    Directory of Open Access Journals (Sweden)

    Satyananda Panda

    2014-01-01

    Full Text Available The flow of a thin liquid film over a heated stretching surface is considered in this study. Due to a potential nonuniform temperature distribution on the stretching sheet, a temperature gradient occurs in the fluid which produces surface tension gradient at the free surface of the thin film. As a result, the free surface deforms and these deformations are advected by the flow in the stretching direction. This work focuses on the inverse problem of reconstructing the sheet temperature distribution and the sheet stretch rate from observed free surface variations. This work builds on the analysis of Santra and Dandapat (2009 who, based on the long-wave expansion of the Navier-Stokes equations, formulate a partial differential equation which describes the evolution of the thickness of a film over a nonisothermal stretched surface. In this work, we show that after algebraic manipulation of a discrete form of the governing equations, it is possible to reconstruct either the unknown temperature field on the sheet and hence the resulting heat transfer or the stretching rate of the underlying surface. We illustrate the proposed methodology and test its applicability on a range of test problems.

  16. Comparison electrical stimulation and passive stretching for blood glucose control type 2 diabetes mellitus patients

    Science.gov (United States)

    Arsianti, Rika Wahyuni; Parman, Dewy Haryanti; Lesmana, Hendy

    2018-04-01

    Physical exercise is one of the cornerstones for management and treatment type 2 diabetes mellitus. But not all people are able to perform physical exercise because of their physical limitation condition. The strategy for those people in this study is electrical stimulation and passive stretching. The aim of this study is to find out the effect of electrical stimulation and passive stretching to lowering blood glucose level. 20 subjects is divided into electrical stimulation and passive stretching group. The provision of electrical stimulation on lower extremities muscles for 30 minutes for electrical stimulation group (N=10). And other underwent passive stretching for 30 minutes (N=10). The result shows that blood glucose level is decrease from 192.9 ± 10.7087 mg/dL to 165.3 ± 10.527 mg/dL for electrical stimulation intervention group while for the passive stretching group the blood glucose decrease from 153 ± 12.468 mg/dL to 136.1 ± 12.346 mg/dL. Both electrical stimulation and passive stretching are effective to lowering blood glucose level and can be proposed for those people restricted to perform exercise.

  17. CH Stretching Region: Computational Modeling of Vibrational Optical Activity

    Czech Academy of Sciences Publication Activity Database

    Hudecová, Jana; Profant, V.; Novotná, P.; Baumruk, V.; Urbanová, M.; Bouř, Petr

    2013-01-01

    Roč. 9, č. 7 (2013), s. 3096-3108 ISSN 1549-9618 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:AV ČR(CZ) M200550902 Institutional support: RVO:61388963 Keywords : density-functional theory * circular-dichroism spectra * N-methyl acetamide * alpha-pinene * Raman Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.310, year: 2013

  18. Elastography Study of Hamstring Behaviors during Passive Stretching.

    Directory of Open Access Journals (Sweden)

    Guillaume Le Sant

    Full Text Available The mechanical properties of hamstring muscles are usually inferred from global passive torque/angle relationships, in combination with adjoining tissues crossing the joint investigated. Shear modulus measurement provides an estimate of changes in muscle-tendon stiffness and passive tension. This study aimed to assess the passive individual behavior of each hamstring muscle in different stretching positions using shear wave elastography.The muscle shear modulus of each hamstring muscle was measured during a standardized slow passive knee extension (PKE, 80% of maximal range of motion on eighteen healthy male volunteers. Firstly, we assessed the reliability of the measurements. Results were good for semitendinosus (ST, CV: 8.9%-13.4%, semimembranosus (SM, CV: 10.3%-11.2% and biceps femoris long-head (BF-lh, CV: 8.6%-13.3%, but not for biceps femoris short-head (BF-sh, CV: 20.3%-44.9%. Secondly, we investigated each reliable muscle in three stretch positions: 70°, 90° and 110° of hip flexion. The results showed different values of shear modulus for the same amount of perceived stretch, with the highest measurements in the high-flexed hip situation. Moreover, individual muscles displayed different values, with values increasing or BF-lh, SM and ST, respectively. The inter-subject variability was 35.3% for ST, 27.4% for SM and 30.2% for BF-lh.This study showed that the hip needs to be high-flexed to efficiently tension the hamstrings, and reports a higher muscle-tendon stress tolerance at 110° of hip angle. In addition muscles have different passive behaviors, and future works will clarify if it can be linked with rate of injury.

  19. Elastography Study of Hamstring Behaviors during Passive Stretching

    Science.gov (United States)

    Le Sant, Guillaume; Ates, Filiz; Brasseur, Jean-Louis; Nordez, Antoine

    2015-01-01

    Introduction The mechanical properties of hamstring muscles are usually inferred from global passive torque/angle relationships, in combination with adjoining tissues crossing the joint investigated. Shear modulus measurement provides an estimate of changes in muscle-tendon stiffness and passive tension. This study aimed to assess the passive individual behavior of each hamstring muscle in different stretching positions using shear wave elastography. Methods/Results The muscle shear modulus of each hamstring muscle was measured during a standardized slow passive knee extension (PKE, 80% of maximal range of motion) on eighteen healthy male volunteers. Firstly, we assessed the reliability of the measurements. Results were good for semitendinosus (ST, CV: 8.9%-13.4%), semimembranosus (SM, CV: 10.3%-11.2%) and biceps femoris long-head (BF-lh, CV: 8.6%-13.3%), but not for biceps femoris short-head (BF-sh, CV: 20.3%-44.9%). Secondly, we investigated each reliable muscle in three stretch positions: 70°, 90° and 110° of hip flexion. The results showed different values of shear modulus for the same amount of perceived stretch, with the highest measurements in the high-flexed hip situation. Moreover, individual muscles displayed different values, with values increasing or BF-lh, SM and ST, respectively. The inter-subject variability was 35.3% for ST, 27.4% for SM and 30.2% for BF-lh. Conclusion This study showed that the hip needs to be high-flexed to efficiently tension the hamstrings, and reports a higher muscle-tendon stress tolerance at 110° of hip angle. In addition muscles have different passive behaviors, and future works will clarify if it can be linked with rate of injury. PMID:26418862

  20. Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility.

    Science.gov (United States)

    Wong, Del P; Chaouachi, Anis; Lau, Patrick W C; Behm, David G

    2011-01-01

    This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key pointsThe duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001).No significant differences in RSA and COD between the 3 stretching conditions.The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects.The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.

  1. Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility

    Science.gov (United States)

    Wong, Del P.; Chaouachi, Anis; Lau, Patrick W.C.; Behm, David G.

    2011-01-01

    This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key points The duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). No significant differences in RSA and COD between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. PMID:24149890

  2. Comparison of the effects of hamstring stretching using proprioceptive neuromuscular facilitation with prior application of cryotherapy or ultrasound therapy

    Science.gov (United States)

    Magalhães, Francisco Elezier Xavier; Junior, Arlindo Rodrigues de Mesquita; Meneses, Harnold’s Tyson de Sousa; Moreira dos Santos, Rayele Pricila; Rodrigues, Ezaine Costa; Gouveia, Samara Sousa Vasconcelos; Gouveia, Guilherme Pertinni de Morais; Orsini, Marco; Bastos, Victor Hugo do Vale; Machado, Dionis de Castro Dutra

    2015-01-01

    [Purpose] Stretching using proprioceptive neuromuscular facilitation involve physiological reflex mechanisms through submaximal contraction of agonists which activate Golgi organ, promoting the relaxation reflex. The aim of this study was to evaluate the effects of proprioceptive neuromuscular facilitation alone and with prior application of cryotherapy and thermotherapy on hamstring stretching. [Subjects and Methods] The sample comprised of 32 young subjects with hamstring retraction of the right limb. The subjects were randomly allocated to four groups: the control, flexibility PNF, flexibility PNF associated with cryotherapy, flexibility PNF in association with ultrasound therapy. [Results] After 12 stretching sessions, experimental groups showed significant improvements compared to the control group. Moreover, we did not find any significant differences among the experimental groups indicating PNF stretching alone elicits similar results to PNF stretching with prior administration of cryotherapy or thermotherapy. [Conclusion] PNF without other therapy may be a more practical and less expensive choice for clinical care. PMID:26157261

  3. Boosting Memory by tDCS to Frontal or Parietal Brain Regions? A Study of the Enactment Effect Shows No Effects for Immediate and Delayed Recognition

    Directory of Open Access Journals (Sweden)

    Beat Meier

    2018-06-01

    Full Text Available Boosting memory with transcranial direct current stimulation (tDCS seems to be an elegant way to optimize learning. Here we tested whether tDCS to the left dorsolateral prefrontal cortex or to the left posterior parietal cortex would boost recognition memory in general and/or particularly for action phrases enacted at study. During study, 48 young adults either read or enacted simple action phrases. Memory for the action phrases was assessed after a retention interval of 45 min and again after 7-days to investigate the long-term consequences of brain stimulation. The results showed a robust enactment effect in both test sessions. Moreover, the decrease in performance was more pronounced for reading than for enacting the phrases at study. However, tDCS did not reveal any effect on subsequent recognition memory performance. We conclude that memory benefits of tDCS are not easily replicated. In contrast, enactment at study reliably boosts subsequent memory.

  4. Effects of Combining Running and Practical Duration Stretching on Proprioceptive Skills of National Sprinters.

    Science.gov (United States)

    Romero-Franco, Natalia; Párraga-Montilla, Juan Antonio; Molina-Flores, Enrique M; Jiménez-Reyes, Pedro

    2018-06-01

    Romero-Franco, N, Párraga-Montilla, JA, Molina-Flores, EM, and Jiménez-Reyes, P. Effects of combining running and practical duration stretching on proprioceptive skills of national sprinters. J Strength Cond Res XX(X): 000-000, 2018-Practical duration stretching after aerobic activities is a recommended component of the first part of warm-up because of its effects on performance. However, its effects on proprioceptive skills are unknown. This study aimed to analyze the effects of running and practical duration static stretching (SS) and dynamic stretching (DS) on postural balance and the joint position sense (JPS) of national sprinters. Thirty-two national sprinters were randomly classified into a SS group (n = 11), DS group (n = 11), or control group (n = 10). Static stretching performed 5 minutes of running and short-duration (20 seconds) static stretches; DS performed 5 minutes of running and short-duration dynamic (20 seconds) stretches; and the control group performed 5 minutes of running. Before and after the intervention, unipedal static postural balance and knee JPS were evaluated. Static stretching exhibited a more centralized center of pressure in the medial-lateral plane for unipedal static postural balance in right-leg support after stretching (p = 0.005, d = 1.24), whereas DS showed values further from the center after stretching for the same unipedal support compared with baseline (p = 0.042, d = 0.49), and the control group remained stable (p > 0.05). Joint position sense did not show significant differences in any group (p > 0.05). In conclusion, combining running and practical duration SS may be beneficial for right-leg postural stabilization, whereas DS may be partly and slightly deleterious. Both SS and DS combined with running and running alone have neutral effects on knee JPS. Sports professionals should consider running and practical duration SS as part of the warm-up of sprinters to partly improve unipedal static postural balance.

  5. Activation of stretch-activated channels and maxi-K+ channels by membrane stress of human lamina cribrosa cells.

    LENUS (Irish Health Repository)

    Irnaten, Mustapha

    2009-01-01

    The lamina cribrosa (LC) region of the optic nerve head is considered the primary site of damage in glaucomatous optic neuropathy. Resident LC cells have a profibrotic potential when exposed to cyclical stretch. However, the mechanosensitive mechanisms of these cells remain unknown. Here the authors investigated the effects of membrane stretch on cell volume change and ion channel activity and examined the associated changes in intracellular calcium ([Ca(2+)](i)).

  6. Stretched horizons, quasiparticles, and quasinormal modes

    International Nuclear Information System (INIS)

    Iizuka, Norihiro; Kabat, Daniel; Lifschytz, Gilad; Lowe, David A.

    2003-01-01

    We propose that stretched horizons can be described in terms of a gas of noninteracting quasiparticles. The quasiparticles are unstable, with a lifetime set by the imaginary part of the lowest quasinormal mode frequency. If the horizon arises from an AdS-CFT style duality the quasiparticles are also the effective low-energy degrees of freedom of the finite-temperature CFT. We analyze a large class of models including Schwarzschild black holes, nonextremal Dp-branes, the rotating BTZ black hole and de Sitter space, and we comment on degenerate horizons. The quasiparticle description makes manifest the relationship between entropy and area

  7. Viscous flows stretching and shrinking of surfaces

    CERN Document Server

    Mehmood, Ahmer

    2017-01-01

    This authored monograph provides a detailed discussion of the boundary layer flow due to a moving plate. The topical focus lies on the 2- and 3-dimensional case, considering axially symmetric and unsteady flows. The author derives a criterion for the self-similar and non-similar flow, and the turbulent flow due to a stretching or shrinking sheet is also discussed. The target audience primarily comprises research experts in the field of boundary layer flow, but the book will also be beneficial for graduate students.

  8. SHORT DURATIONS OF STATIC STRETCHING WHEN COMBINED WITH DYNAMIC STRETCHING DO NOT IMPAIR REPEATED SPRINTS AND AGILITY

    Directory of Open Access Journals (Sweden)

    Del P. Wong

    2011-06-01

    Full Text Available This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA and change of direction (COD. Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s. Three dynamic stretching exercises of 30 s duration were then performed (90 s total. Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p < 0.001. However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (< 90 s static stretching may not have provided sufficient stimulus to elicit performance impairments

  9. An examination of the stretching practices of Division I and Division III college football programs in the midwestern United States.

    Science.gov (United States)

    Judge, Lawrence W; Craig, Bruce; Baudendistal, Steve; Bodey, Kimberly J

    2009-07-01

    Research supports the use of preactivity warm-up and stretching, and the purpose of this study was to determine whether college football programs follow these guidelines. Questionnaires designed to gather demographic, professional, and educational information, as well as specific pre- and postactivity practices, were distributed via e-mail to midwestern collegiate programs from NCAA Division I and III conferences. Twenty-three male coaches (12 from Division IA schools and 11 from Division III schools) participated in the study. Division I schools employed certified strength coaches (CSCS; 100%), whereas Division III schools used mainly strength coordinators (73%), with only 25% CSCS. All programs used preactivity warm-up, with the majority employing 2-5 minutes of sport-specific jogging/running drills. Pre stretching (5-10 minutes) was performed in 19 programs (91%), with 2 (9%) performing no pre stretching. Thirteen respondents used a combination of static/proprioceptive neuromuscular facilitation/ballistic and dynamic flexibility, 5 used only dynamic flexibility, and 1 used only static stretching. All 12 Division I coaches used stretching, whereas only 9 of the 11 Division III coaches did (p = 0.22). The results indicate that younger coaches did not use pre stretching (p = 0.30). The majority of the coaches indicated that they did use post stretching, with 11 of the 12 Division I coaches using stretching, whereas only 5 of the 11 Division III coaches used stretching postactivity (p = 0.027). Divisional results show that the majority of Division I coaches use static-style stretching (p = 0.049). The results of this study indicate that divisional status, age, and certification may influence how well research guidelines are followed. Further research is needed to delineate how these factors affect coaching decisions.

  10. Twist-stretch profiles of DNA chains

    Science.gov (United States)

    Zoli, Marco

    2017-06-01

    Helical molecules change their twist number under the effect of a mechanical load. We study the twist-stretch relation for a set of short DNA molecules modeled by a mesoscopic Hamiltonian. Finite temperature path integral techniques are applied to generate a large ensemble of possible configurations for the base pairs of the sequence. The model also accounts for the bending and twisting fluctuations between adjacent base pairs along the molecules stack. Simulating a broad range of twisting conformation, we compute the helix structural parameters by averaging over the ensemble of base pairs configurations. The method selects, for any applied force, the average twist angle which minimizes the molecule’s free energy. It is found that the chains generally over-twist under an applied stretching and the over-twisting is physically associated to the contraction of the average helix diameter, i.e. to the damping of the base pair fluctuations. Instead, assuming that the maximum amplitude of the bending fluctuations may decrease against the external load, the DNA molecule first over-twists for weak applied forces and then untwists above a characteristic force value. Our results are discussed in relation to available experimental information albeit for kilo-base long molecules.

  11. Stretched Exponential relaxation in pure Se glass

    Science.gov (United States)

    Dash, S.; Ravindren, S.; Boolchand, P.

    A universal feature of glasses is the stretched exponential relaxation, f (t) = exp[ - t / τ ] β . The model of diffusion of excitations to randomly distributed traps in a glass by Phillips1 yields the stretched exponent β = d[d +2] where d, the effective dimensionality. We have measured the enthalpy of relaxation ΔHnr (tw) at Tg of Se glass in modulated DSC experiments as glasses age at 300K and find β = 0.43(2) for tw in the 0

  12. Stretch sensors for human body motion

    Science.gov (United States)

    O'Brien, Ben; Gisby, Todd; Anderson, Iain A.

    2014-03-01

    Sensing motion of the human body is a difficult task. From an engineers' perspective people are soft highly mobile objects that move in and out of complex environments. As well as the technical challenge of sensing, concepts such as comfort, social intrusion, usability, and aesthetics are paramount in determining whether someone will adopt a sensing solution or not. At the same time the demands for human body motion sensing are growing fast. Athletes want feedback on posture and technique, consumers need new ways to interact with augmented reality devices, and healthcare providers wish to track recovery of a patient. Dielectric elastomer stretch sensors are ideal for bridging this gap. They are soft, flexible, and precise. They are low power, lightweight, and can be easily mounted on the body or embedded into clothing. From a commercialisation point of view stretch sensing is easier than actuation or generation - such sensors can be low voltage and integrated with conventional microelectronics. This paper takes a birds-eye view of the use of these sensors to measure human body motion. A holistic description of sensor operation and guidelines for sensor design will be presented to help technologists and developers in the space.

  13. Curved Piezoelectric Actuators for Stretching Optical Fibers

    Science.gov (United States)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    Assemblies containing curved piezoceramic fiber composite actuators have been invented as means of stretching optical fibers by amounts that depend on applied drive voltages. Piezoceramic fiber composite actuators are conventionally manufactured as sheets or ribbons that are flat and flexible, but can be made curved to obtain load-carrying ability and displacement greater than those obtainable from the flat versions. In the primary embodiment of this invention, piezoceramic fibers are oriented parallel to the direction of longitudinal displacement of the actuators so that application of drive voltage causes the actuator to flatten, producing maximum motion. Actuator motion can be transmitted to the optical fiber by use of hinges and clamp blocks. In the original application of this invention, the optical fiber contains a Bragg grating and the purpose of the controlled stretching of the fiber is to tune the grating as part of a small, lightweight, mode-hop-free, rapidly tunable laser for demodulating strain in Bragg-grating strain-measurement optical fibers attached to structures. The invention could also be used to apply controllable tensile force or displacement to an object other than an optical fiber.

  14. MHD biconvective flow of Powell Eyring nanofluid over stretched surface

    Science.gov (United States)

    Naseem, Faiza; Shafiq, Anum; Zhao, Lifeng; Naseem, Anum

    2017-06-01

    The present work is focused on behavioral characteristics of gyrotactic microorganisms to describe their role in heat and mass transfer in the presence of magnetohydrodynamic (MHD) forces in Powell-Eyring nanofluids. Implications concerning stretching sheet with respect to velocity, temperature, nanoparticle concentration and motile microorganism density were explored to highlight influential parameters. Aim of utilizing microorganisms was primarily to stabilize the nanoparticle suspension due to bioconvection generated by the combined effects of buoyancy forces and magnetic field. Influence of Newtonian heating was also analyzed by taking into account thermophoretic mechanism and Brownian motion effects to insinuate series solutions mediated by homotopy analysis method (HAM). Mathematical model captured the boundary layer regime that explicitly involved contemporary non linear partial differential equations converted into the ordinary differential equations. To depict nanofluid flow characteristics, pertinent parameters namely bioconvection Lewis number Lb, traditional Lewis number Le, bioconvection Péclet number Pe, buoyancy ratio parameter Nr, bioconvection Rayleigh number Rb, thermophoresis parameter Nt, Hartmann number M, Grashof number Gr, and Eckert number Ec were computed and analyzed. Results revealed evidence of hydromagnetic bioconvection for microorganism which was represented by graphs and tables. Our findings further show a significant effect of Newtonian heating over a stretching plate by examining the coefficient values of skin friction, local Nusselt number and the local density number. Comparison was made between Newtonian fluid and Powell-Eyring fluid on velocity field and temperature field. Results are compared of with contemporary studies and our findings are found in excellent agreement with these studies.

  15. Stretched exponential dynamics of coupled logistic maps on a small-world network

    Science.gov (United States)

    Mahajan, Ashwini V.; Gade, Prashant M.

    2018-02-01

    We investigate the dynamic phase transition from partially or fully arrested state to spatiotemporal chaos in coupled logistic maps on a small-world network. Persistence of local variables in a coarse grained sense acts as an excellent order parameter to study this transition. We investigate the phase diagram by varying coupling strength and small-world rewiring probability p of nonlocal connections. The persistent region is a compact region bounded by two critical lines where band-merging crisis occurs. On one critical line, the persistent sites shows a nonexponential (stretched exponential) decay for all p while for another one, it shows crossover from nonexponential to exponential behavior as p → 1 . With an effectively antiferromagnetic coupling, coupling to two neighbors on either side leads to exchange frustration. Apart from exchange frustration, non-bipartite topology and nonlocal couplings in a small-world network could be a reason for anomalous relaxation. The distribution of trap times in asymptotic regime has a long tail as well. The dependence of temporal evolution of persistence on initial conditions is studied and a scaling form for persistence after waiting time is proposed. We present a simple possible model for this behavior.

  16. Effects of hamstring stretch with pelvic control on pain and work ability in standing workers.

    Science.gov (United States)

    Han, Hyun-Il; Choi, Ho-Suk; Shin, Won-Seob

    2016-11-21

    Hamstring tightness induces posterior pelvic tilt and decreased lumbar lordosis, which can result in low back painOBJECTIVE: We investigated effects of hamstring stretch with pelvic control on pain and work ability in standing workers. One hundred adult volunteers from a standing workers were randomly assigned to pelvic control hamstring stretching (PCHS) (n = 34), general hamstring stretching (GHS) (n = 34), control (n = 32) groups. The control group was performed self-home exercise. All interventions were conducted 3 days per week for 6 weeks, and included in the hamstring stretching and lumbopelvic muscle strengthening. Outcomes were evaluated through the visual analog scale (VAS), straight leg raise test (SLR), sit and reach test (SRT), Oswestry disability index (ODI), and work ability index (WAI). Significant difference in VAS, SLR, SRT, ODI, and WAI were found in the PCHS and GHS groups. The control group was a significant difference only in ODI. The PCHS group showed a greater difference than the GHS group and control group in VAS, SLR, SRT, and ODI. The pelvic control hamstring stretch exercise would be more helpful in back pain reduction and improvement of work ability in an industrial setting.

  17. Constellation Stretch Goals: Review of Industry Inputs

    Science.gov (United States)

    Lang, John

    2006-01-01

    Many good ideas received based on industry experience: a) Shuttle operations; b) Commercial aircraft production; c) NASA's historical way of doing business; d) Military and commercial programs. Aerospace performed preliminary analysis: a) Potential savings; b) Cost of implementation; c) Performance or other impact/penalties; d) Roadblocks; e) Unintended consequences; f) Bottom line. Significant work ahead for a "Stretch Goal"to become a good, documented requirement: 1) As a group, the relative "value" of goals are uneven; 2) Focused analysis on each goal is required: a) Need to ensure that a new requirement produces the desired consequence; b) It is not certain that some goals will not create problems elsewhere. 3) Individual implementation path needs to be studied: a) Best place to insert requirement (what level, which document); b) Appropriate wording for the requirement. Many goals reflect "best practices" based on lessons learned and may have value beyond near-term CxP requirements process.

  18. LABOR GYMNASTICS: STRETCHING EXERCISE X FLEXIONAMENT

    Directory of Open Access Journals (Sweden)

    Jacqueline Amorin Anchieta Borges da Silva, Isabel Cristina Taranto e Fernanda Piasecki

    2006-12-01

    Full Text Available Nowadays, there are many opportunities for the society to live a healthful and long life. At the same time, never people was so sedentary and without harmony. Without a healthy body and with “an occupied mind” the human loses exactly what more it needs: the disposal to produce, to coexist and to live a good life. In this context, the present research aimed to revise some terms related to labor gymnastics, which is focused in the prevention of risks related to hours of working and in the reduction of muscular tension levels that may be originated during a day of work. Thus, the present study will make a differentiation between the use of stretching and flexionament during labor gymnastic sessions.

  19. Loads applied to fixations for chain stretching

    Energy Technology Data Exchange (ETDEWEB)

    Ahrens, K; Brychta, P

    1985-06-01

    The chains of scraper chain conveyors must be pre-stretched during standstill in order to compensate the elongations occurring during operation. They require frequent retensiening in order to meet the varying operational requirements. During tensioning, the chains are fixed in a point in the top run by means of fixation elements. The authors present a method for calculating the retaining force needed in the fixations. There are three different initial conditions of the chain before trensioning: Tensionsfree chain, pretensioned chain (stressed chain), slack chain. In all three cases, it is important to find out whether or nor the tensioning drive reaches full speed. The method of calculation is illustrated by the example of a scraper chain conveyor; it enables the establishment of rules for tensioning without damaging the chain and is a good basis for the dimensioning of new types of fixation elements.

  20. Aerothermodynamic properties of stretched flames in enclosures

    Science.gov (United States)

    Rotman, D. A.; Oppenheim, A. K.

    Flames are stretched by being pulled along their frontal surface by the flow field in which they reside. Their trajectories tend to approach particle paths, acquiring eventually the role of contact boundaries, -interfaces between the burnt and unburnt medium that may broaden solely as a consequence of diffusion. Fundamental properties of flow fields governing such flames are determined here on the basis of the zero Mach number model, providng a rational method of approach to the computational analysis of combustion fields in enclosures where, besides the aerodynamic properties flow, the thermodynamic process of compression must be taken into account. To illustrate its application, the method is used to reveal the mechanism of formation of a tulip-shape flame in a rectangular enclosure under nonturbulent flow conditions.

  1. Calcineurin /NFAT activation-dependence of leptin synthesis and vascular growth in response to mechanical stretch

    Directory of Open Access Journals (Sweden)

    Nadia Soudani

    2016-09-01

    Full Text Available Background and Aims- Hypertension and obesity are important risk factors of cardiovascular disease. They are both associated with high leptin levels and have been shown to promote vascular hypertrophy, through the RhoA/ROCK and ERK1/2 phosphorylation. Calcineurin/NFAT activation also induces vascular hypertrophy by upregulating various genes. This study aimed to decipher whether a crosstalk exists between the RhoA/ROCK pathway, Ca+2/calcineurin/NFAT pathway, and ERK1/2 phosphorylation in the process of mechanical stretch-induced vascular smooth muscle cell (VSMC hypertrophy and leptin synthesis. Methods and Results- Rat portal vein (RPV organ culture was used to investigate the effect of mechanical stretch and exogenous leptin (3.1 nM on VSMC hypertrophy and leptin synthesis. Results showed that stretching the RPV significantly upregulated leptin secretion, mRNA and protein expression, which were inhibited by the calcium channel blocker nifedipine (10 μM, the selective calcineurin inhibitor FK506 (1 nM and the ERK1/2 inhibitor PD98059 (1 μM. The transcription inhibitor actinomycin D (0.1M and the translation inhibitor cycloheximide (1 mM significantly decreased stretch-induced leptin protein expression. Mechanical stretch or leptin caused an increase in wet weight changes and protein synthesis, considered as hypertrophic markers, while they were inhibited by FK506 (0.1 nM; 1 nM. In addition, stretch or exogenous leptin significantly increased calcineurin activity and MCIP1 expression whereas leptin induced NFAT nuclear translocation in VSMCs. Moreover, in response to stretch or exogenous leptin, the Rho inhibitor C3 exoenzyme (30 ng/mL, the ROCK inhibitor Y-27632 (10 μM, and the actin depolymerization agents Latrunculin B (50 nM and cytochalasin D (1 μM reduced calcineurin activation and NFAT nuclear translocation. ERK1/2 phosphorylation was inhibited by FK506 and C3. Conclusions- Mechanical stretch-induced VSMC hypertrophy and leptin

  2. The effects of two methods of reflexology and stretching exercises on the severity of restless leg syndrome among hemodialysis patients.

    Science.gov (United States)

    Shahgholian, Nahid; Jazi, Shahrzad Khojandi; Karimian, Jahangir; Valiani, Mahboubeh

    2016-01-01

    Restless leg syndrome prevalence is high among the patients undergoing hemodialysis. Due to several side effects of medicational treatments, the patients prefer non-medicational methods. Therefore, the present study aimed to investigate the effects of two methods of reflexology and stretching exercises on the severity of restless leg syndrome among patients undergoing hemodialysis. This study is a randomized clinical trial that was done on 90 qualified patients undergoing hemodialysis in selected hospitals of Isfahan, who were diagnosed with restless leg syndrome through standard restless leg syndrome questionnaire. They were randomly assigned by random number table to three groups: Reflexology, stretching exercises, and control groups through random allocation. Foot reflexology and stretching exercises were conducted three times a week for 30-40 min within straight 4 weeks. Data analysis was performed by SPSS version 18 using descriptive and inferential statistical analyses [one-way analysis of variance (ANOVA), paired t-test, and least significant difference (LSD) post hoc test]. There was a significant difference in the mean scores of restless leg syndrome severity between reflexology and stretching exercises groups, compared to control (P reflexology and stretching exercises groups compared to the control group (P reflexology massage and stretching exercises groups. Our obtained results showed that reflexology and stretching exercises can reduce the severity of restless leg syndrome. These two methods of treatment are recommended to the patients.

  3. Randomized Trial of Modified Stretching Exercise Program for Menstrual Low Back Pain.

    Science.gov (United States)

    Chen, Huei-Mein; Hu, Hsou-Mei

    2018-03-01

    This study aimed to examine the effectiveness of a modified stretching exercise program on young women with menstrual low back pain. Overall, 127 young women were randomly assigned to the experimental ( n = 63) and control ( n = 64) groups. The experimental group followed the modified stretching exercise program, whereas the control group performed their usual activities. At 1, 4, 8, and 12 months, the experimental group had significantly lower scores on the visual analog scale for pain (95% confidence interval [CI] = [0.73, 1.96]; p < .05) and the Oswestry Low Back Pain Disability Questionnaire than the control group (95% CI = [0.68, 2.03]; p < .001). At 12 months, the experimental group showed significantly higher exercise self-efficacy than the control group (95% CI = [-6.87, 0.62]; p = .003). These findings can be used to enhance self-care capabilities by using the modified stretching exercise program for young women with menstrual low back pain.

  4. Wiener Index, Diameter, and Stretch Factor of a Weighted Planar Graph in Subquadratic Time

    DEFF Research Database (Denmark)

    Wulff-Nilsen, Christian

    over all pairs of distinct vertices of the ratio between the graph distance and the Euclidean distance between the two vertices). More specifically, we show that the Wiener index and diameter can be found in O(n^2*(log log n)^4/log n) worst-case time and that the stretch factor can be found in O(n^2......We solve three open problems: the existence of subquadratic time algorithms for computing the Wiener index (sum of APSP distances) and the diameter (maximum distance between any vertex pair) of a planar graph with non-negative edge weights and the stretch factor of a plane geometric graph (maximum...

  5. Self-induced stretch syncope of adolescence: a video-EEG documentation.

    Science.gov (United States)

    Mazzuca, Michel; Thomas, Pierre

    2007-12-01

    We present the first video-EEG documentation, with ECG and EMG features, of stretch syncope of adolescence in a young, healthy 16-year-old boy. Stretch syncope of adolescence is a rarely reported, benign cause of fainting in young patients, which can be confused with epileptic seizures. In our patient, syncopes were self-induced to avoid school. Dynamic transcranial Doppler showed evidence of blood flow decrease in both posterior cerebral arteries mimicking effects of a Valsalva manoeuvre. Dynamic angiogram of the vertebral arteries was normal. Hypotheses concerning the physiopathology are discussed. [Published with video sequences].

  6. Computing the Stretch Factor of Paths, Trees, and Cycles in Weighted Fixed Orientation Metrics

    DEFF Research Database (Denmark)

    Wulff-Nilsen, Christian

    2008-01-01

    Let G be a graph embedded in the L_1-plane. The stretch factor of G is the maximum over all pairs of distinct vertices p and q of G of the ratio L_1^G(p,q)/L_1(p,q), where L_1^G(p,q) is the L_1-distance in G between p and q. We show how to compute the stretch factor of an n-vertex path in O(n*(log...... n)^2) worst-case time and O(n) space and we mention generalizations to trees and cycles, to general weighted fixed orientation metrics, and to higher dimensions....

  7. Motion of Knots in DNA Stretched by Elongational Fields

    Science.gov (United States)

    Klotz, Alexander R.; Soh, Beatrice W.; Doyle, Patrick S.

    2018-05-01

    Knots in DNA occur in biological systems, serve as a model system for polymer entanglement, and affect the efficacy of modern genomics technologies. We study the motion of complex knots in DNA by stretching molecules with a divergent electric field that provides an elongational force. We demonstrate that the motion of knots is nonisotropic and driven towards the closest end of the molecule. We show for the first time experimentally that knots can go from a mobile to a jammed state by varying an applied strain rate, and that this jamming is reversible. We measure the mobility of knots as a function of strain rate, demonstrating the conditions under which knots can be driven towards the ends of the molecule and untied.

  8. The stretch reflex and the contributions of C David Marsden

    Directory of Open Access Journals (Sweden)

    Kalyan B Bhattacharyya

    2017-01-01

    Full Text Available The stretch reflex or myotatic reflex refers to the contraction of a muscle in response to its passive stretching by increasing its contractility as long as the stretch is within physiological limits. For ages, it was thought that the stretch reflex was of short latency and it was synonymous with the tendon reflex, subserving the same spinal reflex arc. However, disparities in the status of the two reflexes in certain clinical situations led Marsden and his collaborators to carry out a series of experiments that helped to establish that the two reflexes had different pathways. That the two reflexes are dissociated has been proved by the fact that the stretch reflex and the tendon reflex, elicited by stimulation of the same muscle, have different latencies, that of the stretch reflex being considerably longer. They hypothesized that the stretch reflex had a transcortical course before it reached the spinal motor neurons for final firing. Additionally, the phenomenon of stimulus-sensitive cortical myoclonus lent further evidence to the presence of the transcortical loop where the EEG correlate preceded the EMG discharge. This concept has been worked out by later neurologists in great detail , and the general consensus is that indeed, the stretch reflex is endowed with a conspicuous transcortical component.

  9. Possible stretched exponential parametrization for humidity absorption in polymers.

    Science.gov (United States)

    Hacinliyan, A; Skarlatos, Y; Sahin, G; Atak, K; Aybar, O O

    2009-04-01

    Polymer thin films have irregular transient current characteristics under constant voltage. In hydrophilic and hydrophobic polymers, the irregularity is also known to depend on the humidity absorbed by the polymer sample. Different stretched exponential models are studied and it is shown that the absorption of humidity as a function of time can be adequately modelled by a class of these stretched exponential absorption models.

  10. Effectiveness of the Simultaneous Stretching of the Achilles Tendon and Plantar Fascia in Individuals With Plantar Fasciitis.

    Science.gov (United States)

    Engkananuwat, Phoomchai; Kanlayanaphotporn, Rotsalai; Purepong, Nithima

    2018-01-01

    Since the plantar fascia and the Achilles tendon are anatomically connected, it is plausible that stretching of both structures simultaneously will result in a better outcome for plantar fasciitis. Fifty participants aged 40 to 60 years with a history of plantar fasciitis greater than 1 month were recruited. They were prospectively randomized into 2 groups. Group 1 was instructed to stretch the Achilles tendon while group 2 simultaneously stretched the Achilles tendon and plantar fascia. After 4 weeks of both stretching protocols, participants in group 2 demonstrated a significantly greater pressure pain threshold than participants in group 1 ( P = .040) with post hoc analysis. No significant differences between groups were demonstrated in other variables ( P > .05). Concerning within-group comparisons, both interventions resulted in significant reductions in pain at first step in the morning and average pain at the medial plantar calcaneal region over the past 24 hours, while there were increases in the pressure pain threshold, visual analog scale-foot and ankle score, and range of motion in ankle dorsiflexion ( P plantar fascia for 4 weeks was a more effective intervention for plantar fasciitis. Patients who reported complete relief from symptoms at the end of the 4-week intervention in the simultaneous stretching group (n = 14; 56%) were double that of the stretching of the Achilles tendon-only group (n = 7; 28%). II, lesser quality RCT or prospective comparative study.

  11. Effect of Kinesiotaping and Stretching Exercise on Forward Shoulder Angle in Females with Rounded Shoulder Posture

    Directory of Open Access Journals (Sweden)

    Arghavan Hajibashi

    2014-12-01

    Full Text Available Background: Rounded shoulder posture is a common abnormal posture in upper quarter. Kinesiotape is a new intervention that recently used in rehabilitation. There are no studies have examined the effect of kinesiotape on rounded shoulder posture. Therefore the purpose of this study was to determine the effect of scapular kinesiotaping and pectoralis minor stretching exercise on forward shoulder angle in female subjects with rounded shoulder posture. Methods: Twenty female students aged between 18 to 25 years old with rounded shoulder posture participated in this study. Then, the subjects were randomly and equally assigned to two groups: the stretch group and the stretch plus kinesiotape group. Both groups were trained for doing home exercise to stretch Pectoralis minor bilaterally for two weeks. Kinesiotape group received kinesiotape on scapular area additionally. Forward shoulder angle was measured in four sessions including pre-intervention (first session, immediately after the first intervention (second session, fourth day (third session and at the end of two weeks (fourth session. Two-way repeated measures ANOVA (4×2 was used for data analysis. Results: kinesiotape group showed significant within-group decrease in forward shoulder angle between first session with three other sessions (P≤0.05.There was no significant within-group difference in stretch group and between groups (P=0.20 forward shoulder angle-by-group interaction in measurement sessions was significantly different (P=0.02 Conclusion: scapular kinesiotaping along with pectoralis minor stretching exercise improved rounded shoulder posture in subjects of the present study. kinesiotape is suggested as a complem

  12. Piezo Is Essential for Amiloride-Sensitive Stretch-Activated Mechanotransduction in Larval Drosophila Dorsal Bipolar Dendritic Sensory Neurons.

    Science.gov (United States)

    Suslak, Thomas J; Watson, Sonia; Thompson, Karen J; Shenton, Fiona C; Bewick, Guy S; Armstrong, J Douglas; Jarman, Andrew P

    2015-01-01

    Stretch-activated afferent neurons, such as those of mammalian muscle spindles, are essential for proprioception and motor co-ordination, but the underlying mechanisms of mechanotransduction are poorly understood. The dorsal bipolar dendritic (dbd) sensory neurons are putative stretch receptors in the Drosophila larval body wall. We have developed an in vivo protocol to obtain receptor potential recordings from intact dbd neurons in response to stretch. Receptor potential changes in dbd neurons in response to stretch showed a complex, dynamic profile with similar characteristics to those previously observed for mammalian muscle spindles. These profiles were reproduced by a general in silico model of stretch-activated neurons. This in silico model predicts an essential role for a mechanosensory cation channel (MSC) in all aspects of receptor potential generation. Using pharmacological and genetic techniques, we identified the mechanosensory channel, DmPiezo, in this functional role in dbd neurons, with TRPA1 playing a subsidiary role. We also show that rat muscle spindles exhibit a ruthenium red-sensitive current, but found no expression evidence to suggest that this corresponds to Piezo activity. In summary, we show that the dbd neuron is a stretch receptor and demonstrate that this neuron is a tractable model for investigating mechanisms of mechanotransduction.

  13. Bruxism: Is There an Indication for Muscle-Stretching Exercises?

    Science.gov (United States)

    Gouw, Simone; de Wijer, Anton; Creugers, Nico Hj; Kalaykova, Stanimira I

    Bruxism is a common phenomenon involving repetitive activation of the masticatory muscles. Muscle-stretching exercises are a recommended part of several international guidelines for musculoskeletal disorders and may be effective in management of the jaw muscle activity that gives rise to bruxism. However, most studies of muscle-stretching exercises have mainly focused on their influence on performance (eg, range of motion, coordination, and muscle strength) of the limb or trunk muscles of healthy individuals or individuals with sports-related injuries. Very few have investigated stretching of the human masticatory muscles and none muscle-stretching exercises in the management of (sleep) bruxism. This article reviews the literature on muscle-stretching exercises and their potential role in the management of sleep bruxism or its consequences in the musculoskeletal system.

  14. Acute effect of different stretching methods on isometric muscle strength

    Directory of Open Access Journals (Sweden)

    Gabriel Vasconcellos de Lima Costa e Silva

    2014-03-01

    This study investigated the acute effect of static stretching methods (SS and proprioceptive neuromuscular facilitation (PNF on the static muscle strength (SMS. Eleven young male subjects with strength training experience, performed 3 tests with a 48h interval between them, randomly selected, where each one subject carried out all procedures: a hand grip without stretching; b hand grip preceded by static stretching of wrist flexors muscles; c hand grip preceded by PNF stretching of wrist flexors muscles. The Shapiro-Wilk test verified the normality of data, and a one-way ANOVA with repeated measures, followed by Tukey’s post hoc test, evaluated the differences between the groups. The significance was set at p 0.05. In conclusion, both stretching methods had caused negative effects on isometric strength, reducing its levels.

  15. Mixed quantum/classical approach to OH-stretch inelastic incoherent neutron scattering spectroscopy for ambient and supercooled liquid water and ice Ih

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2015-07-07

    OH-stretch inelastic incoherent neutron scattering (IINS) has been measured to determine the vibrational density of states (VDOS) in the OH-stretch region for liquid water, supercooled water, and ice Ih, providing complementary information to IR and Raman spectroscopies about hydrogen bonding in these phases. In this work, we extend the combined electronic-structure/molecular-dynamics (ES/MD) method, originally developed by Skinner and co-workers to simulate OH-stretch IR and Raman spectra, to the calculation of IINS spectra with small k values. The agreement between theory and experiment in the limit k → 0 is reasonable, further validating the reliability of the ES/MD method in simulating OH-stretch spectroscopy in condensed phases. The connections and differences between IINS and IR spectra are analyzed to illustrate the advantages of IINS over IR in estimating the OH-stretch VDOS.

  16. Mixed quantum/classical approach to OH-stretch inelastic incoherent neutron scattering spectroscopy for ambient and supercooled liquid water and ice Ih

    International Nuclear Information System (INIS)

    Shi, L.; Skinner, J. L.

    2015-01-01

    OH-stretch inelastic incoherent neutron scattering (IINS) has been measured to determine the vibrational density of states (VDOS) in the OH-stretch region for liquid water, supercooled water, and ice Ih, providing complementary information to IR and Raman spectroscopies about hydrogen bonding in these phases. In this work, we extend the combined electronic-structure/molecular-dynamics (ES/MD) method, originally developed by Skinner and co-workers to simulate OH-stretch IR and Raman spectra, to the calculation of IINS spectra with small k values. The agreement between theory and experiment in the limit k → 0 is reasonable, further validating the reliability of the ES/MD method in simulating OH-stretch spectroscopy in condensed phases. The connections and differences between IINS and IR spectra are analyzed to illustrate the advantages of IINS over IR in estimating the OH-stretch VDOS

  17. A Stream Function Theory Based Calculation of Wave Kinematics for Very Steep Waves Using a Novel Non-linear Stretching Technique

    DEFF Research Database (Denmark)

    Stroescu, Ionut Emanuel; Sørensen, Lasse; Frigaard, Peter Bak

    2016-01-01

    A non-linear stretching method was implemented for stream function theory to solve wave kinematics for physical conditions close to breaking waves in shallow waters, with wave heights limited by the water depth. The non-linear stretching method proves itself robust, efficient and fast, showing good...

  18. Short pulse generation from a passively mode-locked fiber optical parametric oscillator with optical time-stretch.

    Science.gov (United States)

    Qiu, Yi; Wei, Xiaoming; Du, Shuxin; Wong, Kenneth K Y; Tsia, Kevin K; Xu, Yiqing

    2018-04-16

    We propose a passively mode-locked fiber optical parametric oscillator assisted with optical time-stretch. Thanks to the lately developed optical time-stretch technique, the onset oscillating spectral components can be temporally dispersed across the pump envelope and further compete for the parametric gain with the other parts of onset oscillating sidebands within the pump envelope. By matching the amount of dispersion in optical time-stretch with the pulse width of the quasi-CW pump and oscillating one of the parametric sidebands inside the fiber cavity, we numerically show that the fiber parametric oscillator can be operated in a single pulse regime. By varying the amount of the intracavity dispersion, we further verify that the origin of this single pulse mode-locking regime is due to the optical pulse stretching and compression.

  19. Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

    DEFF Research Database (Denmark)

    Balle, S S; Magnusson, S P; McHugh, M P

    2015-01-01

    The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength wa...

  20. On nature of spontaneous elongation of polymers preliminarily stretched in adsorption-active media under irradiation

    International Nuclear Information System (INIS)

    Sinevich, E.A.; Prazdnichnyj, A.M.; Tikhomirov, V.S.; Bakeev, N.F.

    1989-01-01

    The nature of the spontaneous elongation under irradiation with fast electrons of polymers preliminary stretched in adsorption-active media has been studied. This effect is related with radiation-induced heating of microporous polymer samples. Its manifestation in amorphous PETP requires the presence of crazes having well developed microfibrillar structure. The spontaneous elongation effect is shown to be a result of crystallization of partially oriented material in transitional regions relating the oriented material of microfibrils inside crazes with nonstrained polymer between them

  1. STUDY TO COMPARE THE EFFECTIVENESS OF STATIC STRETCH AND HOLD RELAX TECHNIQUE OVER HAMSTRING FLEXIBILITY

    Directory of Open Access Journals (Sweden)

    Shanthi C

    2014-10-01

    Full Text Available Background: Numerous studies have documented on flexibility of muscles. Flexibility is defined as the ability of the muscles to lengthen allowing one joint or more than one joint in a series to move through a range of motion .Flexibility allows tissue to accommodate more easily to stress thus minimizing or preventing muscle injury. But this study sought to identify the study to compare the effectiveness of Static stretch and Hold relax technique over the hamstring flexibility. Methods: 30 healthy male adults with Hamstring tightness aged 21 to 35 years selected from general population through simple randomized technique. Samples are divided into two groups, static stretch Group-I(no.15 and Group-II Hold relax (no.=15.The outcome was measured with help of sit & reach test to see the Hamstring flexibility. Results: Comparison of the post test values of the group I and group II shows a significant difference between the outcomes of two groups with a “t” calculated value of 0.738 (unpaired “t” test. Conclusion: Both static stretch and hold relax Technique can cause very highly significant result in Hamstring Flexibility, further comparison shows very high significant difference between two groups and concludes that hold relax is better than static stretch in Hamstring Flexibility.

  2. New Insights into Lamellar Structure Development and SAXS/WAXD Sequence Appearance During Uniaxial Stretching of Amorphous Poly(ethylene terephthalate) Above Glass Transition Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kawakami,D.; Burger, C.; Ran, S.; Avila-Orta, C.; Sics, I.; Chu, B.; Chiao, S.; Hsiao, B.; Kikutani, T.

    2008-01-01

    An in situ study of structure formation in amorphous poly(ethylene terephthalate) (PET) during uniaxial stretching at a temperature 30 C above glass transition temperature was carried out using synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. Three major deformation-induced structure transitions were confirmed. (1) At small strains, the applied load increased initially but leveled off afterward. Sporadic isotropic crystallization without preferred orientation was observed by WAXD, where no hierarchical structure was seen by SAXS. (2) At intermediate strains, strain hardening took place. Although WAXD showed persistent progression of isotropic crystallization, SAXS indicated formation of a layered structure as well as a fibrillar domain in large scale. This behavior is not consistent with the mechanisms for shish-kebab or spinodal-assisted structure formation. Instead, it can be explained by flow-induced demixing of crystal and amorphous phases through layerlike flocking motion perpendicular to the stretching direction. (3) At high strains, the ratio between the applied load and strain was about constant. In this stage, crystal reorientation and lateral crystal growth took place. The corresponding structure changes could be categorized into three subregions. In the first region, the (010) crystalline plane began to orient. In the second region, the (100) crystalline plane began to orient. In the last region, the structure change became stable and the sample eventually broke apart.

  3. Magnitude and duration of stretch modulate fibroblast remodeling.

    Science.gov (United States)

    Balestrini, Jenna L; Billiar, Kristen L

    2009-05-01

    Mechanical cues modulate fibroblast tractional forces and remodeling of extracellular matrix in healthy tissue, healing wounds, and engineered matrices. The goal of the present study is to establish dose-response relationships between stretch parameters (magnitude and duration per day) and matrix remodeling metrics (compaction, strength, extensibility, collagen content, contraction, and cellularity). Cyclic equibiaxial stretch of 2-16% was applied to fibroblast-populated fibrin gels for either 6 h or 24 h/day for 8 days. Trends in matrix remodeling metrics as a function of stretch magnitude and duration were analyzed using regression analysis. The compaction and ultimate tensile strength of the tissues increased in a dose-dependent manner with increasing stretch magnitude, yet remained unaffected by the duration in which they were cycled (6 h/day versus 24 h/day). Collagen density increased exponentially as a function of both the magnitude and duration of stretch, with samples stretched for the reduced duration per day having the highest levels of collagen accumulation. Cell number and failure tension were also dependent on both the magnitude and duration of stretch, although stretch-induced increases in these metrics were only present in the samples loaded for 6 h/day. Our results indicate that both the magnitude and the duration per day of stretch are critical parameters in modulating fibroblast remodeling of the extracellular matrix, and that these two factors regulate different aspects of this remodeling. These findings move us one step closer to fully characterizing culture conditions for tissue equivalents, developing improved wound healing treatments and understanding tissue responses to changes in mechanical environments during growth, repair, and disease states.

  4. Characterizing the stretch-flangeability of hot rolled multiphase steels

    International Nuclear Information System (INIS)

    Pathak, N.; Butcher, C.; Worswick, M.; Gao, J.

    2013-01-01

    Hole expansion tests are commonly used to characterize the edge stretching limit of a material. Traditionally, a conical punch is used to expand a punched hole until a through-thickness crack appears. However, many automotive stretch flanging operations involve in-plane edge stretching that is best captured with a flat punch. In this paper, hole expansion tests were carried out on two different hot-rolled multiphase steels using both flat and conical punches. The fracture mechanisms for both punch types were investigated using scanning electron microscopy (SEM)

  5. COMPARISON OF EFFECTS OF ABDOMINAL STRETCHING EXERCISE AND COLD COMPRESS THERAPY ON MENSTRUAL PAIN INTENSITY IN TEENAGE GIRLS

    Directory of Open Access Journals (Sweden)

    Desta Ayu Cahya Rosyida

    2017-07-01

    Full Text Available Background: Pain during menstruation is not uncommon, especially in young women, which has an impact on their life activities. Objective: To examine the effect of abdominal stretching exercise and cold compress therapy on decreasing intensity of menstrual pain in teenage girls at SMK Bakti Indonesia Medika. Design: A Quasy Experimental Study with two group comparison pretest-postest design. There were 46 respondents selected in this study by consecutive sampling that consisted of 23 samples in the abdominal stretching exercise group and 23 samples in the cold compress group. The menstrual pain was measured using VAS (visual analog scale. Data were analyzed using Mann-Whitney, Chi-Square, and Wilcoxon test. Results: Findings showed that the mean of menstrual pain before intervention in the abdominal stretching exercise was 7.04 and in the cold compress therapy was 6.74 with p-value 0.211 (<0.05, which indicated that there was no mean difference of pain between both groups. However, after intervention, the menstrual pain was reduced from 7.04 to 1.91 (5.09 difference in the abdominal stretching exercise group; and from 6.74 to 5.52 (1.22 difference in the cold compress group with p-value 0.000 (<0.05, which indicated that there was statistically significant difference of menstrual pain before and after intervention, both abdominal stretching exercise and cold compress therapy. Conclusion: There were statistically significant effects of abdominal stretching exercise and cold compress therapy on menstrual pain in teenage girls. The abdominal stretching exercise is more effective than cold compress therapy in reducing menstrual pain intensity. Thus, it is suggested that abdominal stretching exercise can be an alternative choice of management of dysmenorrhea in teenage girls, and can be a part of subject in the education as non-pharmacological medicine.

  6. Effect of hip and knee position on tensor fasciae latae elongation during stretching: An ultrasonic shear wave elastography study.

    Science.gov (United States)

    Umehara, Jun; Ikezoe, Tome; Nishishita, Satoru; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Fujita, Kosuke; Ichihashi, Noriaki

    2015-12-01

    Decreased flexibility of the tensor fasciae latae is one factor that causes iliotibial band syndrome. Stretching has been used to improve flexibility or tightness of the muscle. However, no studies have investigated the effective stretching position for the tensor fasciae latae using an index to quantify muscle elongation in vivo. The aim of this study was to investigate the effects of hip rotation and knee angle on tensor fasciae latae elongation during stretching in vivo using ultrasonic shear wave elastography. Twenty healthy men participated in this study. The shear elastic modulus of the tensor fasciae latae was calculated using ultrasonic shear wave elastography. Stretching was performed at maximal hip adduction and maximal hip extension in 12 different positions with three hip rotation conditions (neutral, internal, and external rotations) and four knee angles (0°, 45°, 90°, and 135°). Two-way analysis of variance showed a significant main effect for knee angle, but not for hip rotation. The post-hoc test for knee angle indicated that the shear elastic modulus at 90° and 135° were significantly greater than those at 0° and 45°. Our results suggest that adding hip rotation to the stretching position with hip adduction and extension may have less effect on tensor fasciae latae elongation, and that stretching at >90° of knee flexion may effectively elongate the tensor fasciae latae. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Individually programmable cell stretching microwell arrays actuated by a Braille display.

    Science.gov (United States)

    Kamotani, Yoko; Bersano-Begey, Tommaso; Kato, Nobuhiro; Tung, Yi-Chung; Huh, Dongeun; Song, Jonathan W; Takayama, Shuichi

    2008-06-01

    Cell culture systems are often static and are therefore nonphysiological. In vivo, many cells are exposed to dynamic surroundings that stimulate cellular responses in a process known as mechanotransduction. To recreate this environment, stretchable cell culture substrate systems have been developed, however, these systems are limited by being macroscopic and low throughput. We have developed a device consisting of 24 miniature cell stretching chambers with flexible bottom membranes that are deformed using the computer-controlled, piezoelectrically actuated pins of a Braille display. We have also developed efficient image capture and analysis protocols to quantify morphological responses of the cells to applied strain. Human dermal microvascular endothelial cells (HDMECs) were found to show increasing degrees of alignment and elongation perpendicular to the radial strain in response to cyclic stretch at increasing frequencies of 0.2, 1, and 5 Hz, after 2, 4, and 12h. Mouse myogenic C2C12 cells were also found to align in response to the stretch, while A549 human lung adenocarcinoma epithelial cells did not respond to stretch.

  8. A COMPARATIVE STUDY ON EFFECTIVENESS OF STATIC STRETCH AND HOLD RELAX TECHNIQUES OVER HAMSTRING FLEXIBILITY

    Directory of Open Access Journals (Sweden)

    N. Vamsidhar

    2014-12-01

    Full Text Available Background: Flexibility is important in prevention of injury, muscular and postural imbalance more over the Hamstring flexibility has a lion share in sports performances and preventing DOMS. Stretching procedures increases the ROM by embarking on biomechanics and Neurologic and molecular mechanics. Hamstrings, the two joint muscle plays a crucial role in two joints integrity and also spine as they are in closed kinematic chain. The hamstring muscles represent the primary flexors of Knee. Hamstrings tightness results in Limits Knee extension when hip is flexed, Posterior Pelvic tilt, and flatten the lumbar spine. Methods: The subjects selected randomly and divided into two groups (Experimental group and control group.30 samples in One group applied with Static Stretch once a day for 3 repetitions 5 days a week for six weeks and 30 samples in other group applied with Hold relax technique once a day for 4 repetitions 5 days a week for six weeks. The knee joint range of motion was measured at the end of every week with Universal goniometer. Results: By comparing the means of Group – I, given Static Stretch and Group – II, given Hold relax Technique for six weeks implied that there is improvement of flexibility in Group – II and the ‘P’ value < 0.01 shows the difference is highly significant. Conclusion: This study concludes that the hold relax Technique method has proved to be better technique then the static stretch for improving hamstring flexibility.

  9. Kink and kink-like waves in pre-stretched Mooney-Rivlin viscoelastic rods

    Directory of Open Access Journals (Sweden)

    Y. Z. Wang

    2015-08-01

    Full Text Available The present paper theoretically investigates kink and kink-like waves propagating in pre-stretched Mooney-Rivlin viscoelastic rods. In the constitutive modeling, the Cauchy stress tensor is assumed to consist of an elastic part and a dissipative part. The asymptotic method is adopted to simplify the nonlinear dynamic equations in the limit of finite-small amplitude and long wavelength. Using the reductive perturbation method, we further derive the well-known far-field equation (i.e. the KdV-Burgers equation, to which two kinds of explicit traveling wave solutions are presented. Examples are given to show the influences of pre-stretch and viscosity on the wave shape and wave velocity. It is shown that pre-stretch could be an effective method for modulating the two types of waves. In addition, such waves may be utilized to measure the viscosity coefficient of the material. The competition between the effects of pre-stretch and viscosity on the kink and kink-like waves is also revealed.

  10. Tip opening of premixed bunsen flames: Extinction with negative stretch and local Karlovitz number

    KAUST Repository

    Vu, Tranmanh

    2015-04-01

    The characteristics of tip openings in premixed bunsen flames have been studied experimentally by measuring OH radicals from laser-induced fluorescence and tip curvatures from chemiluminescent images. Results showed that the tip opening occurred at a constant equivalence ratio and was independent of the jet velocity in propane/air mixtures. The observation of a local extinction phenomenon of the negatively stretched flame due to the flame curvature could not be consistently explained based on flame stretch or the Karlovitz number, since they varied appreciably with the jet velocity. The concept of the local Karlovitz number (KaL) was introduced, which is defined as the ratio of the characteristic reaction time in the normal direction for a stretched flame to the characteristic flow time in the tangential direction for the stretched flame. The local Karlovitz number maintained a constant value under tip opening conditions, irrespective of the jet velocity. Tip opening occurred at a reasonably constant local Karlovitz number of about ~1.72 when the nitrogen dilution level in propane and n-butane fuels was varied.

  11. Modeling stretched solitary waves along magnetic field lines

    Directory of Open Access Journals (Sweden)

    L. Muschietti

    2002-01-01

    Full Text Available A model is presented for a new type of fast solitary waves which is observed in downward current regions of the auroral zone. The three-dimensional, coherent structures are electrostatic, have a positive potential, and move along the magnetic field lines with speeds on the order of the electron drift. Their parallel potential profile is flattened and cannot fit to the Gaussian shape used in previous work. We develop a detailed BGK model which includes a flattened potential and an assumed cylindrical symmetry around a centric magnetic field line. The model envisions concentric shells of trapped electrons slowly drifting azimuthally while bouncing back and forth in the parallel direction. The electron dynamics is analysed in terms of three basic motions that occur on different time scales characterized by the cyclotron frequency We , the bounce frequency wb , and the azimuthal drift frequency wg. The ordering We >> wb >> wg is required. Self-consistent distribution functions are calculated in terms of approximate constants of motion. Constraints on the parameters characterizing the amplitude and shape of the stretched solitary wave are discussed.

  12. GRAVITATIONALLY UNSTABLE FLAMES: RAYLEIGH-TAYLOR STRETCHING VERSUS TURBULENT WRINKLING

    International Nuclear Information System (INIS)

    Hicks, E. P.; Rosner, R.

    2013-01-01

    In this paper, we provide support for the Rayleigh-Taylor-(RT)-based subgrid model used in full-star simulations of deflagrations in Type Ia supernovae explosions. We use the results of a parameter study of two-dimensional direct numerical simulations of an RT unstable model flame to distinguish between the two main types of subgrid models (RT or turbulence dominated) in the flamelet regime. First, we give scalings for the turbulent flame speed, the Reynolds number, the viscous scale, and the size of the burning region as the non-dimensional gravity (G) is varied. The flame speed is well predicted by an RT-based flame speed model. Next, the above scalings are used to calculate the Karlovitz number (Ka) and to discuss appropriate combustion regimes. No transition to thin reaction zones is seen at Ka = 1, although such a transition is expected by turbulence-dominated subgrid models. Finally, we confirm a basic physical premise of the RT subgrid model, namely, that the flame is fractal, and thus self-similar. By modeling the turbulent flame speed, we demonstrate that it is affected more by large-scale RT stretching than by small-scale turbulent wrinkling. In this way, the RT instability controls the flame directly from the large scales. Overall, these results support the RT subgrid model.

  13. [Sciatica. From stretch rack to microdiscectomy].

    Science.gov (United States)

    Gruber, P; Böni, T

    2015-12-01

    In ancient times as well as in the Middle Ages treatment options for discogenic nerve compression syndrome were limited and usually not very specific because of low anatomical and pathophysiological knowledge. The stretch rack (scamnum Hippocratis) was particularly prominent but was widely used as a therapeutic device for very different spinal disorders. Since the beginning of the nineteenth century anatomical knowledge increased and the advances in the fields of asepsis, anesthesia and surgery resulted in an increase in surgical interventions on the spine. In 1908 the first successful lumbar discectomy was initiated and performed by the German neurologist Heinrich O. Oppenheim (1858-1919) and the surgeon Fedor Krause (1857-1937); however, neither recognized the true pathological condition of discogenic nerve compression syndrome. With the landmark report in the New England Journal of Medicine in 1934, the two American surgeons William Jason Mixter (1880-1958) and Joseph Seaton Barr (1901-1963) finally clarified the pathomechanism of lumbar disc herniation and furthermore, propagated discectomy as the standard therapy. Since then interventions on intervertebral discs rapidly increased and the treatment options for lumbar disc surgery quickly evolved. The surgical procedures changed over time and were continuously being refined. In the late 1960s the surgical microscope was introduced for spinal surgery by the work of the famous neurosurgeon Mahmut Gazi Yasargil and his colleague Wolfhard Caspar and so-called microdiscectomy was introduced. Besides open discectomy other interventional techniques were developed to overcome the side effects of surgical procedures. In 1964 the American orthopedic surgeon Lyman Smith (1912-1991) introduced chemonucleolysis, a minimally invasive technique consisting only of a cannula and the proteolytic enzyme chymopapain, which is injected into the disc compartment to dissolve the displaced disc material. In 1975 the Japanese orthopedic

  14. Effects of Static Stretching and Playing Soccer on Knee Laxity

    NARCIS (Netherlands)

    Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W.; Freiwald, Juergen

    Objective: This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Design: Randomized controlled trial. Setting: University biomechanics laboratory. Participants: Thirty-one athletes were randomly assigned into

  15. Effects of Static Stretching and Playing Soccer on Knee Laxity

    NARCIS (Netherlands)

    Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W.; Freiwald, Juergen

    2015-01-01

    Objective: This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Design: Randomized controlled trial. Setting: University biomechanics laboratory. Participants: Thirty-one athletes were randomly assigned into

  16. Guidelines for Stretch Flanging Advanced High Strength Steels

    International Nuclear Information System (INIS)

    Sriram, S.; Chintamani, J.

    2005-01-01

    Advanced High Strength Steels (AHSS) are currently being considered for use in closure and structural panels in the automotive industry because of their high potential for affordable weight reduction and improved performance. AHSS such as dual phase steels are currently being used in some vehicle platforms. From a manufacturing perspective, stretch flanging during stamping is an important deformation mode requiring careful consideration of geometry and the die process. This paper presents some geometric and process guidelines for stretch flanging AHSS. Hole expansion experiments were conducted to determine the failure limit for a sheared edge condition. Effects of punching clearance, prestrain and prior strain path on hole expansion were explored in these experiments. In addition, dynamic explicit FE calculations using LS-DYNA were also conducted for a typical stretch flange by varying some key geometric parameters. The experimental and FEA results were then analyzed to yield process and geometric guidelines to enable successful stretch flanging of AHSS

  17. Damage percolation during stretch flange forming of aluminum alloy sheet

    Science.gov (United States)

    Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

    2005-12-01

    A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to "calibrate" proper nucleation strains for both alloys.

  18. Stretched flow of Carreau nanofluid with convective boundary ...

    Indian Academy of Sciences (India)

    journal of. January 2016 physics pp. 3–17. Stretched flow of Carreau nanofluid with ... fluid over a flat plate subjected to convective surface condition. ... the steady laminar boundary layer flow over a permeable plate with a convective boundary.

  19. Equibiaxial cyclic stretch stimulates fibroblasts to rapidly remodel fibrin.

    Science.gov (United States)

    Balestrini, Jenna Leigh; Billiar, Kristen Lawrence

    2006-01-01

    Understanding the effects of the mechanical environment on wound healing is critical for developing more effective treatments to reduce scar formation and contracture. The aim of this study was to investigate the effects of dynamic mechanical stretch on cell-mediated early wound remodeling independent of matrix alignment which obscures more subtle remodeling mechanisms. Cyclic equibiaxial stretch (16% stretch at 0.2 Hz) was applied to fibroblast-populated fibrin gel in vitro wound models for eight days. Compaction, density, tensile strength, and collagen content were quantified as functional measures of remodeling. Stretched samples were approximately ten times stronger, eight-fold more dense, and eight times thinner than statically cultured samples. These changes were accompanied by a 15% increase in net collagen but no significant differences in cell number or viability. When collagen crosslinking was inhibited in stretched samples, the extensibility increased and the strength decreased. The apparent weakening was due to a reduction in compaction rather than a decrease in ability of the tissue to withstand tensile forces. Interestingly, inhibiting collagen crosslinking had no measurable effects on the statically cultured samples. These results indicate that amplified cell-mediated compaction and even a slight addition in collagen content play substantial roles in mechanically induced wound strengthening. These findings increase our understanding of how mechanical forces guide the healing response in skin, and the methods employed in this study may also prove valuable tools for investigating stretch-induced remodeling of other planar connective tissues and for creating mechanically robust engineered tissues.

  20. Acute effect of static stretching on muscle force in older women

    Directory of Open Access Journals (Sweden)

    André Luiz Demantova Gurjão

    2010-04-01

    Full Text Available The objective of this study was to investigate the acute effect of static stretching on the peak rate of force development (PRFD and maximum voluntary contraction (MVC in older women. Ten women (68.5 ± 7.0 years; 70.9 ± 8.1 kg; 159.4 ± 6.0 cm; body mass index: 28.0 ± 3.8 kg/m2 were studied. MVC and PRFD were determined by leg press exercise before and after the control or stretching condition (three sets of 30 seconds of static stretching of the quadriceps on two different days (interval of 24 hours. PRFD was determined as the steepest slope of the curve, calculated within regular windows of 20 milliseconds (∆force/∆time for the first 200 milliseconds after the onset of contraction. MVC was determined as the highest value recorded in each set. Only one condition was tested on each day and the order of application of each condition was determined randomly. The stretching intensity was evaluated by the muscle pain threshold. Four post-condition assessments (post-treatment, 10, 20, and 30 minutes were performed to monitor muscle strength. ANCOVA 2x5, followed by the Scheffé post-hoc test, showed no significant interactions between conditions vs. times (P > 0.05 for PRFD or MVC. In conclusion, acute bouts of static stretching of the quadriceps femoris do not affect the ability of rapid and maximum muscle force production in older women.

  1. Linear response of stretch-affected premixed flames to flow oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.Y.; Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Lieuwen, T. [School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2009-04-15

    The linear response of 2D wedge-shaped premixed flames to harmonic velocity disturbances was studied, allowing for the influence of flame stretch manifested as variations in the local flame speed along the wrinkled flame front. Results obtained from analyzing the G-equation show that the flame response is mainly characterized by a Markstein number {sigma}{sub C}, which measures the curvature effect of the wrinkles, and a Strouhal number, St{sub f}, defined as the angular frequency of the disturbance normalized by the time taken for the disturbance to propagate the flame length. Flame stretch is found to become important when the disturbance frequency satisfies {sigma}{sub C}St{sub f}{sup 2}{proportional_to} O(1), i.e. St{sub f}{proportional_to} O({sigma}{sub C}{sup -1/2}). Specifically, for disturbance frequencies below this order, stretch effects are small and the flame responds as an unstretched one. When the disturbance frequencies are of this order, the transfer function, defined as the ratio of the normalized fluctuation of the heat release rate to that of the velocity, is contributed mostly from fluctuations of the flame surface area, which is now affected by stretch. Finally, as the disturbance frequency increases to St{sub f}{proportional_to} O({sigma}{sub C}{sup -1}), i.e. {sigma}{sub C}St{sub f}{proportional_to} O(1), the direct contribution from the stretch-affected flame speed fluctuation to the transfer function becomes comparable to that of the flame surface area. The present study phenomenologically explains the experimentally observed filtering effect in which the flame wrinkles developed at the flame base decay along the flame surface for large frequency disturbances as well as for thermal-diffusively stable and weakly unstable mixtures. (author)

  2. Effect of Active-Assisted Stretching of 30 Seconds and 60 Seconds in Muscle Force

    Directory of Open Access Journals (Sweden)

    Mirian dos Santos Monteiro

    2018-01-01

    Full Text Available This study aims to analyze the interference of the active-assisted stretching technique in muscle strength. Participating in this study were 39 healthy and physically active individuals subdivided into three groups of active-assisted stretching G30 - 30 seconds, G60 - 60 seconds and CG - control. The muscular strength was evaluated using the isokinetic dynamometer, obtaining the analyzed conditions of torque peak, total work and agonist and antagonist relationship of the dorsiflexor and flexor muscles ankle. The values obtained were statistically analyzed by the SPSS from the “t-test for paired sample” (p ≤ 0.05. When analyzing the effect produced by the stretching, it was observed that the 30-second elongation showed a reduction of the average of the muscular torque in all conditions analyzed, with the exception of the relation between the agonist and the left antagonist and the total work of the right plantar flexors, the G60 - 60 seconds group had a reduction in average muscle torque in all conditions analyzed, except for the relation between agonist and left antagonist that obtained an increase in muscle torque and the CG - control group, there was a reduction in the average of the muscular torque in all the analyzed conditions, except for the torque and total work of the left plantar flexor muscles that presented increase. Thus, it can be concluded that there were differences between the groups of active-assisted stretching of 30 and 60 and that the effect produced by stretching did not present a significant reduction of muscle strength.

  3. Development of Aluminum-Lithium 2195 Gores by the Stretch Forming Process

    Science.gov (United States)

    Volz, M. P.; Chen, P. S.; Gorti, S.; Salvail, P.

    2014-01-01

    Aluminum-Lithium alloy 2195 exhibits higher mechanical properties and lower density than aluminum alloy 2219, which is the current baseline material for Space Launch System (SLS) cryogenic tank components. Replacement of Al 2219 with Al-Li 2195 would result in substantial weight savings, as was the case when this replacement was made on the shuttle external tank. A key component of cryogenic tanks are the gores, which are welded together to make the rounded ends of the tanks. The required thicknesses of these gores depend on the specific SLS configuration and may exceed the current experience base in the manufacture of such gores by the stretch forming process. Here we describe the steps taken to enhance the formability of Al-Li 2195 by optimizing the heat treatment and stretch forming processes for gore thicknesses up to 0.75", which envelopes the maximum expected gore thicknesses for SLS tanks. An annealing treatment, developed at Marshall Space Flight Center, increased the forming range and strain hardening exponent of Al-Li 2195 plates. Using this annealing treatment, one 0.525" thick and two 0.75" thick gores were manufactured by the stretch forming process. The annealing treatment enabled the stretch forming of the largest ever cross sectional area (thickness x width) of an Al-Li 2195 plate achieved by the manufacturer. Mechanical testing of the gores showed greater than expected ultimate tensile strength, yield strength, modulus, and elongation values. The gores also exhibited acceptable fracture toughness at room and LN2 temperatures. All of the measured data indicate that the stretch formed gores have sufficient material properties to be used in flight domes.

  4. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects.

    LENUS (Irish Health Repository)

    O'Sullivan, Kieran

    2009-01-01

    BACKGROUND: Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. METHODS: A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. RESULTS: Across both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05). CONCLUSION: Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced

  5. The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects

    Directory of Open Access Journals (Sweden)

    Murray Elaine

    2009-04-01

    Full Text Available Abstract Background Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls. Methods A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM. 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1 at baseline; (2 after warm-up; (3 after stretch (static or dynamic and (4 after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova. Results Across both groups, there was a significant main effect for time (p 0.05. Using ANCOVA to adjust for the non-significant (p = 0.141 baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05. Conclusion Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes. Trial Registration ACTRN12608000638336

  6. Measurement of Resistive Plantar Flexion Torque of the Ankle during Passive Stretch in Healthy Subjects and Patients with Poststroke Hemiplegia.

    Science.gov (United States)

    Mizuno, Shiho; Sonoda, Shigeru; Takeda, Kotaro; Maeshima, Shinichiro

    2016-04-01

    Quantification of increased muscle tone for patients with spasticity has been performed to date using various devices to replace the manual scales, such as the modified Ashworth scale or the Tardieu scale. We developed a device that could measure resistive plantar flexion (PF) torque of the ankle during passive dorsiflexion (DF) as an indicator of muscle tone of ankle plantar flexors. The primary objective was to explore the test-retest intrarater reliability of a custom-built device. Participants were 11 healthy subjects (7 men, 4 women; mean age 47.0 years) and 22 patients with poststroke hemiplegia (11 hemorrhagic, 11 ischemic; 14 men, 8 women; mean age 57.2 years). The device was affixed to the ankle. Subjects were seated with knees either flexed or extended. The ankle was passively dorsiflexed from 20° of PF to more than 10° of DF at 5°/second (slow stretch) or 90°/second (fast stretch). Angle and torque were measured twice during the stretches. The intraclass correlation coefficients (ICCs) of torque at 10° of DF (T10) in the 4 conditions-slow and fast stretches with knee flexed or extended-were calculated. The T10 ICCs of the 4 conditions were .95-.99 in both groups. The healthy subjects showed significantly higher T10 of knee extension than of knee flexion during slow and fast stretches. The patients showed increased velocity-dependent torque during fast stretches. Excellent reliability was observed. The device is suitable for measuring resistive PF torque during passive stretch in a flexed knee condition. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  7. Effect of one stretch a week applied to the immobilized soleus muscle on rat muscle fiber morphology

    Directory of Open Access Journals (Sweden)

    Gomes A.R.S.

    2004-01-01

    Full Text Available We determined the effect of stretching applied once a week to the soleus muscle immobilized in the shortened position on muscle fiber morphology. Twenty-six male Wistar rats weighing 269 ± 26 g were divided into three groups. Group I, the left soleus was immobilized in the shortened position for 3 weeks; group II, the soleus was immobilized in the shortened position and stretched once a week for 3 weeks; group III, the soleus was submitted only to stretching once a week for 3 weeks. The medial part of the soleus muscle was frozen for histology and muscle fiber area evaluation and the lateral part was used for the determination of number and length of serial sarcomeres. Soleus muscle submitted only to immobilization showed a reduction in weight (44 ± 6%, P = 0.002, in serial sarcomere number (23 ± 15% and in cross-sectional area of the fibers (37 ± 31%, P < 0.001 compared to the contralateral muscles. The muscle that was immobilized and stretched showed less muscle fiber atrophy than the muscles only immobilized (P < 0.05. Surprisingly, in the muscles submitted only to stretching, fiber area was decreased compared to the contralateral muscle (2548 ± 659 vs 2961 ± 806 µm², respectively, P < 0.05. In conclusion, stretching applied once a week for 40 min to the soleus muscle immobilized in the shortened position was not sufficient to prevent the reduction of muscle weight and of serial sarcomere number, but provided significant protection against muscle fiber atrophy. In contrast, stretching normal muscles once a week caused a reduction in muscle fiber area.

  8. The effects of two methods of reflexology and stretching exercises on the severity of restless leg syndrome among hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Nahid Shahgholian

    2016-01-01

    Full Text Available Background: Restless leg syndrome prevalence is high among the patients undergoing hemodialysis. Due to several side effects of medicational treatments, the patients prefer non-medicational methods. Therefore, the present study aimed to investigate the effects of two methods of reflexology and stretching exercises on the severity of restless leg syndrome among patients undergoing hemodialysis. Materials and Methods: This study is a randomized clinical trial that was done on 90 qualified patients undergoing hemodialysis in selected hospitals of Isfahan, who were diagnosed with restless leg syndrome through standard restless leg syndrome questionnaire. They were randomly assigned by random number table to three groups: Reflexology, stretching exercises, and control groups through random allocation. Foot reflexology and stretching exercises were conducted three times a week for 30–40 min within straight 4 weeks. Data analysis was performed by SPSS version 18 using descriptive and inferential statistical analyses [one-way analysis of variance (ANOVA, paired t-test, and least significant difference (LSD post hoc test]. Results: There was a significant difference in the mean scores of restless leg syndrome severity between reflexology and stretching exercises groups, compared to control (P < 0.001, but there was no significant difference between the two study groups (P < 0.001. Changes in the mean score of restless leg syndrome severity were significantly higher in reflexology and stretching exercises groups compared to the control group (P < 0.001, but it showed no significant difference between reflexology massage and stretching exercises groups. Conclusions: Our obtained results showed that reflexology and stretching exercises can reduce the severity of restless leg syndrome. These two methods of treatment are recommended to the patients.

  9. Effects of Static Stretching and Playing Soccer on Knee Laxity.

    Science.gov (United States)

    Baumgart, Christian; Gokeler, Alli; Donath, Lars; Hoppe, Matthias W; Freiwald, Jürgen

    2015-11-01

    This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Randomized controlled trial. University biomechanics laboratory. Thirty-one athletes were randomly assigned into a stretching (26.9 ± 6.2 years, 1.77 ± 0.09 m, 67.9 ± 10.7 kg) and a control group (27.9 ± 7.4 years, 1.75 ± 0.08 m, 72.0 ± 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 ± 5.6 years, 1.74 ± 0.10 m, 71.8 ± 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury. The stretching group performed 4 different static stretching exercises with a duration of 2 × 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes. Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention. There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 ± 1.6 mm (P soccer of 1.0 ± 1.5 mm (P = 0.001). The ATT increase after static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups. Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer. The observed increase in ATT after static stretching and playing soccer may be associated with changes in kinesthetic perception and sensorimotor control, activation of muscles, joint stability, overall performance, and higher injury risk.

  10. Stretched exponential relaxation in molecular and electronic glasses

    Science.gov (United States)

    Phillips, J. C.

    1996-09-01

    Stretched exponential relaxation, 0034-4885/59/9/003/img1, fits many relaxation processes in disordered and quenched electronic and molecular systems, but it is widely believed that this function has no microscopic basis, especially in the case of molecular relaxation. For electronic relaxation the appearance of the stretched exponential is often described in the context of dispersive transport, where 0034-4885/59/9/003/img2 is treated as an adjustable parameter, but in almost all cases it is generally assumed that no microscopic meaning can be assigned to 0034-4885/59/9/003/img3 even at 0034-4885/59/9/003/img4, a glass transition temperature. We show that for molecular relaxation 0034-4885/59/9/003/img5 can be understood, providing that one separates extrinsic and intrinsic effects, and that the intrinsic effects are dominated by two magic numbers, 0034-4885/59/9/003/img6 for short-range forces, and 0034-4885/59/9/003/img7 for long-range Coulomb forces, as originally observed by Kohlrausch for the decay of residual charge on a Leyden jar. Our mathematical model treats relaxation kinetics using the Lifshitz - Kac - Luttinger diffusion to traps depletion model in a configuration space of effective dimensionality, the latter being determined using axiomatic set theory and Phillips - Thorpe constraint theory. The experiments discussed include ns neutron scattering experiments, particularly those based on neutron spin echoes which measure S( Q,t) directly, and the traditional linear response measurements which span the range from 0034-4885/59/9/003/img8 to s, as collected and analysed phenomenologically by Angell, Ngai, Böhmer and others. The electronic materials discussed include a-Si:H, granular 0034-4885/59/9/003/img9, semiconductor nanocrystallites, charge density waves in 0034-4885/59/9/003/img10, spin glasses, and vortex glasses in high-temperature semiconductors. The molecular materials discussed include polymers, network glasses, electrolytes and alcohols, Van

  11. Stretched exponential relaxation in molecular and electronic glasses

    International Nuclear Information System (INIS)

    Phillips, J.C.

    1996-01-01

    Stretched exponential relaxation, exp[-(t/τ) β ], fits many relaxation processes in disordered and quenched electronic and molecular systems, but it is widely believed that this function has no microscopic basis, especially in the case of molecular relaxation. For electronic relaxation the appearance of the stretched exponential is often described in the context of dispersive transport, where β is treated as an adjustable parameter, but in almost all cases it is generally assumed that no microscopic meaning can be assigned to 0 g , a glass transition temperature. We show that for molecular relaxation β(T g ) can be understood, providing that one separates extrinsic and intrinsic effects, and that the intrinsic effects are dominated by two magic numbers, β SR =3/5 for short-range forces, and β K =3/7 for long-range Coulomb forces, as originally observed by Kohlrausch for the decay of residual charge on a Leyden jar. Our mathematical model treats relaxation kinetics using the Lifshitz-Kac-Luttinger diffusion to traps depletion model in a configuration space of effective dimensionality, the latter being determined using axiomatic set theory and Phillips-Thorpe constraint theory. The experiments discussed include ns neutron scattering experiments, particularly those based on neutron spin echoes which measure S(Q, t) directly, and the traditional linear response measurements which span the range from μs to s, as collected and analysed phenomenologically by Angell, Ngai, Boehmer and others. The electronic materials discussed include a-Si:H, granular C 60 , semiconductor nanocrystallites, charge density waves in TaS 3 , spin glasses, and vortex glasses in high-temperature semiconductors. The molecular materials discussed include polymers, network glasses, electrolytes and alcohols, Van der Waals supercooled liquids and glasses, orientational glasses, water, fused salts, and heme proteins. In the intrinsic cases the theory of β(T g ) is often accurate to 2%, which

  12. Extrinsic stretching narrowing and anterior indentation of the rectosigmoid junction

    International Nuclear Information System (INIS)

    Schulman, A.; Fataar, S.

    1979-01-01

    Thirty-five cases of extrinsic narrowing or anterior indentation of the rectosigmoid junction (RSJ) have been studied. The RSJ lies directly behind the pouch of Douglas which is a favoured site for peritoneal metastasis, abscess and endometriosis. Any space-occupying lesion of sufficient size at this site will indent the anterior aspects of the RSJ. Causes include distension or tumour of the ileum or sigmoid colon, gross ascites (when the patient is erect), and tumours below the pelvic peritonium, such as gynaecological neoplasm and internal iliac artery aneurysm. When a desmoplastic metastasis in the pouch of Douglas infiltrates the outer layers of the RSJ, the fibrosis produces an eccentric shortening on its anterior aspect, which in turn causes a pleating of the mucosa with the folds radiating towards the shortened area. This is also seen with primary pelvic carcinomas directly adherent to the rectum, endometriosis with repeated bleeding and increasing eccentric, submucosal fibrosis, and chronic abscess in the pouch of Douglas. Not all extrinsic narrowing of the RSJ are pathological. One case of anterior indentation followed operation for rectal prolapse. Ten additional cases showed narrowing due to a technical artefact air-distended colon rising into the upper abdomen to cause stretching at the RSJ. As with ascites, this narrowing due to 'high-rise sigmoid' disappeared when the patients became recumbent and the colonic air redistributed. (author)

  13. Effectiveness of different exercises and stretching physiotherapy on pain and movement in patellofemoral pain syndrome: a randomized controlled trial.

    Science.gov (United States)

    Moyano, F Revelles; Valenza, M C; Martin, L Martin; Caballero, Y Castellote; Gonzalez-Jimenez, E; Demet, G Valenza

    2013-05-01

    To compare the effectiveness of proprioceptive neuromuscular facilitation combined with exercise, classic stretching physiotherapy intervention, and educational intervention at improving patient function and pain in patients with patellofemoral pain syndrome. Randomized, controlled, blind trial over four months. Urban population, Spain. Patients undergoing primary care for retropatellar pain. Subjects were allocated on three different treatment options: a proprioceptive neuromuscular facilitation and aerobic exercise group, a classic stretching group, and a control treatment were applied over four months under the supervision of a physiotherapist. Knee Society Score, pain reported (Visual analogue scale) and knee range of motion. Assessments were completed at baseline and after four months. 74 patients were enrolled in the study and distributed between groups. Both the proprioceptive neuromuscular facilitation and classic stretching group showed significant changes in all variables after four months intervention (p < 0.001). The difference in mean Kujala knee score changes between groups (classic stretching group vs. proprioceptive neuromuscular facilitation group vs. control group) at four months was -24.05 (95% confidence interval (CI) -30.19, -17.90), p ≤ 0.001; vs. -39.03 (95% confidence interval (CI) -42.5, -35.5), p ≤ 0.001; vs. -0.238 (95% confidence interval (CI) -1.2, 0.726), p = 0.621, respectively. A proprioceptive neuromuscular facilitation intervention protocol combined with aerobic exercise showed a better outcome than a classic stretching protocol after four months.

  14. Expression and proliferation profiles of PKC, JNK and p38MAPK in physiologically stretched human bladder smooth muscle cells

    International Nuclear Information System (INIS)

    Wazir, Romel; Luo, De-Yi; Dai, Yi; Yue, Xuan; Tian, Ye; Wang, Kun-Jie

    2013-01-01

    Highlights: •Stretch induces proliferation in human bladder smooth muscle cells (HBSMC). •5% Equibiaxial elongation produces maximum proliferation. •Physiologic stretch decreases apoptotic cell death. •PKC is involved in functional modulation of bladder. •JNK and p38 are not involved in proliferating HBSMC. -- Abstract: Objective: To determine protein kinase C (PKC), c-Jun NH2-Terminal Kinase (JNK) and P38 mitogen-activated protein kinases (p38MAPK) expression levels and effects of their respective inhibitors on proliferation of human bladder smooth muscle cells (HBSMCs) when physiologically stretched in vitro. Materials and methods: HBSMCs were grown on silicone membrane and stretch was applied under varying conditions; (equibiaxial elongation: 2.5%, 5%, 10%, 15%, 20%, 25%), (frequency: 0.05, 0.1, 0.2, 0.5, 1 Hz). Optimal physiological stretch was established by assessing proliferation with 5-Bromo-2-deoxyuridine (BrdU) assay and flow cytometry. PKC, JNK and p38 expression levels were analyzed by Western blot. Specificity was maintained by employing specific inhibitors; (GF109203X for PKC, SP600125 for JNK and SB203580 for p38MAPK), in some experiments. Results: Optimum proliferation was observed at 5% equibiaxial stretch (BrdU: 0.837 ± 0.026 (control) to 1.462 ± 0.023)%, (P 0.05 SP600125) and (1.461 ± 0.01, P > 0.05 SB203580). These findings show that mechanical stretch can promote magnitude-dependent proliferative modulation through PKC and possibly JNK but not via p38MAPK in hBSMCs

  15. Stretching of a polymer chain anchored to a surface: the massive field theory approach

    International Nuclear Information System (INIS)

    Usatenko, Zoryana

    2014-01-01

    Taking into account the well-known correspondence between the field theoretical φ 4 O(n)-vector model in the limit n → 0 and the behaviour of long-flexible polymer chains, the investigation of stretching of an ideal and a real polymer chain with excluded volume interactions in a good solvent anchored to repulsive and inert surfaces is performed. The calculations of the average stretching force which arises when the free end of a polymer chain moves away from a repulsive or inert surface are performed up to one-loop order of the massive field theory approach in fixed space dimensions d = 3. The analysis of the obtained results indicates that the average stretching force for a real polymer chain anchored to a repulsive surface demonstrates different behaviour for the cases z-tilde ≪1 and z-tilde ≫1, where z-tilde =z ′ /R z . Besides, the results obtained in the framework of the massive field theory approach are in good agreement with previous theoretical results for an ideal polymer chain and results of a density functional theory approach for the region of small applied forces when deformation of a polymer chain in the direction of the applied force is not bigger than the linear extension of a polymer chain in this direction. The better agreement between these two methods is observed in the case where the number of monomers increases and the polymer chain becomes longer. (paper)

  16. Cyclic Stretch Alters Vascular Reactivity of Mouse Aortic Segments

    Directory of Open Access Journals (Sweden)

    Arthur Leloup

    2017-10-01

    Full Text Available Large, elastic arteries buffer the pressure wave originating in the left ventricle and are constantly exposed to higher amplitudes of cyclic stretch (10% than muscular arteries (2%. As a crucial factor for endothelial and smooth muscle cell function, cyclic stretch has, however, never been studied in ex vivo aortic segments of mice. To investigate the effects of cyclic stretch on vaso-reactivity of mouse aortic segments, we used the Rodent Oscillatory Tension Set-up to study Arterial Compliance (ROTSAC. The aortic segments were clamped at frequencies of 6–600 bpm between two variable preloads, thereby mimicking dilation as upon left ventricular systole and recoiling as during diastole. The preloads corresponding to different transmural pressures were chosen to correspond to a low, normal or high amplitude of cyclic stretch. At different time intervals, cyclic stretch was interrupted, the segments were afterloaded and isometric contractions by α1-adrenergic stimulation with 2 μM phenylephrine in the absence and presence of 300 μM L-NAME (eNOS inhibitor and/or 35 μM diltiazem (blocker of voltage-gated Ca2+ channels were measured. As compared with static or cyclic stretch at low amplitude (<10 mN or low frequency (0.1 Hz, cyclic stretch at physiological amplitude (>10 mN and frequency (1–10 Hz caused better ex vivo conservation of basal NO release with time after mounting. The relaxation of PE-precontracted segments by addition of ACh to stimulate NO release was unaffected by cyclic stretch. In the absence of basal NO release (hence, presence of L-NAME, physiological in comparison with aberrant cyclic stretch decreased the baseline tension, attenuated the phasic contraction by phenylephrine in the absence of extracellular Ca2+ and shifted the smaller tonic contraction more from a voltage-gated Ca2+ channel-mediated to a non-selective cation channel-mediated. Data highlight the need of sufficient mechanical activation of endothelial and

  17. Mechanical Stretching Promotes Skin Tissue Regeneration via Enhancing Mesenchymal Stem Cell Homing and Transdifferentiation.

    Science.gov (United States)

    Liang, Xiao; Huang, Xiaolu; Zhou, Yiwen; Jin, Rui; Li, Qingfeng

    2016-07-01

    Skin tissue expansion is a clinical procedure for skin regeneration to reconstruct cutaneous defects that can be accompanied by severe complications. The transplantation of mesenchymal stem cells (MSCs) has been proven effective in promoting skin expansion and helping to ameliorate complications; however, systematic understanding of its mechanism remains unclear. MSCs from luciferase-Tg Lewis rats were intravenously transplanted into a rat tissue expansion model to identify homing and transdifferentiation. To clarify underlying mechanisms, a systematic approach was used to identify the differentially expressed genes between mechanically stretched human MSCs and controls. The biological significance of these changes was analyzed through bioinformatic methods. We further investigated genes and pathways of interest to disclose their potential role in mechanical stretching-induced skin regeneration. Cross sections of skin samples from the expanded group showed significantly more luciferase(+) and stromal cell-derived factor 1α (SDF-1α)(+), luciferase(+)keratin 14(+), and luciferase(+)CD31(+) cells than the control group, indicating MSC transdifferentiation into epidermal basal cells and endothelial cells after SDF-1α-mediated homing. Microarray analysis suggested upregulation of genes related to hypoxia, vascularization, and cell proliferation in the stretched human MSCs. Further investigation showed that the homing of MSCs was blocked by short interfering RNA targeted against matrix metalloproteinase 2, and that mechanical stretching-induced vascular endothelial growth factor A upregulation was related to the Janus kinase/signal transducer and activator of transcription (Jak-STAT) and Wnt signaling pathways. This study determines that mechanical stretching might promote skin regeneration by upregulating MSC expression of genes related to hypoxia, vascularization, and cell proliferation; enhancing transplanted MSC homing to the expanded skin; and

  18. Seabed maps showing topography, ruggedness, backscatter intensity, sediment mobility, and the distribution of geologic substrates in Quadrangle 6 of the Stellwagen Bank National Marine Sanctuary Region offshore of Boston, Massachusetts

    Science.gov (United States)

    Valentine, Page C.; Gallea, Leslie B.

    2015-11-10

    The U.S. Geological Survey (USGS), in cooperation with the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program, has conducted seabed mapping and related research in the Stellwagen Bank National Marine Sanctuary (SBNMS) region since 1993. The area is approximately 3,700 square kilometers (km2) and is subdivided into 18 quadrangles. Seven maps, at a scale of 1:25,000, of quadrangle 6 (211 km2) depict seabed topography, backscatter, ruggedness, geology, substrate mobility, mud content, and areas dominated by fine-grained or coarse-grained sand. Interpretations of bathymetric and seabed backscatter imagery, photographs, video, and grain-size analyses were used to create the geology-based maps. In all, data from 420 stations were analyzed, including sediment samples from 325 locations. The seabed geology map shows the distribution of 10 substrate types ranging from boulder ridges to immobile, muddy sand to mobile, rippled sand. Mapped substrate types are defined on the basis of sediment grain-size composition, surface morphology, sediment layering, the mobility or immobility of substrate surfaces, and water depth range. This map series is intended to portray the major geological elements (substrates, topographic features, processes) of environments within quadrangle 6. Additionally, these maps will be the basis for the study of the ecological requirements of invertebrate and vertebrate species that utilize these substrates and guide seabed management in the region.

  19. Stretch-sensitive paresis and effort perception in hemiparesis.

    Science.gov (United States)

    Vinti, Maria; Bayle, Nicolas; Hutin, Emilie; Burke, David; Gracies, Jean-Michel

    2015-08-01

    In spastic paresis, stretch applied to the antagonist increases its inappropriate recruitment during agonist command (spastic co-contraction). It is unknown whether antagonist stretch: (1) also affects agonist recruitment; (2) alters effort perception. We quantified voluntary activation of ankle dorsiflexors, effort perception, and plantar flexor co-contraction during graded dorsiflexion efforts at two gastrocnemius lengths. Eighteen healthy (age 41 ± 13) and 18 hemiparetic (age 54 ± 12) subjects performed light, medium and maximal isometric dorsiflexion efforts with the knee flexed or extended. We determined dorsiflexor torque, Root Mean Square EMG and Agonist Recruitment/Co-contraction Indices (ARI/CCI) from the 500 ms peak voluntary agonist recruitment in a 5-s maximal isometric effort in tibialis anterior, soleus and medial gastrocnemius. Subjects retrospectively reported effort perception on a 10-point visual analog scale. During gastrocnemius stretch in hemiparetic subjects, we observed: (1) a 25 ± 7 % reduction of tibialis anterior voluntary activation (maximum reduction 98 %; knee extended vs knee flexed; p = 0.007, ANOVA); (2) an increase in dorsiflexion effort perception (p = 0.03, ANCOVA). Such changes did not occur in healthy subjects. Effort perception depended on tibialis anterior recruitment only (βARI(TA) = 0.61, p hemiparesis, voluntary ability to recruit agonist motoneurones is impaired--sometimes abolished--by antagonist stretch, a phenomenon defined here as stretch-sensitive paresis. In addition, spastic co-contraction increases effort perception, an additional incentive to evaluate and treat this phenomenon.

  20. Stretch activates myosin light chain kinase in arterial smooth muscle

    International Nuclear Information System (INIS)

    Barany, K.; Rokolya, A.; Barany, M.

    1990-01-01

    Stretching of porcine carotid arterial muscle increased the phosphorylation of the 20 kDa myosin light chain from 0.23 to 0.68 mol [32P]phosphate/mol light chain, whereas stretching of phorbol dibutyrate treated muscle increased the phosphorylation from 0.30 to 0.91 mol/mol. Two-dimensional gel electrophoresis followed by two-dimensional tryptic phosphopeptide mapping was used to identify the enzyme involved in the stretch-induced phosphorylation. Quantitation of the [32P]phosphate content of the peptides revealed considerable light chain phosphorylation by protein kinase C only in the phorbol dibutyrate treated arterial muscle, whereas most of the light chain phosphorylation was attributable to myosin light chain kinase. Upon stretch of either the untreated or treated muscle, the total increment in [32P]phosphate incorporation into the light chain could be accounted for by peptides characteristic for myosin light chain kinase catalyzed phosphorylation, demonstrating that the stretch-induced phosphorylation is caused by this enzyme exclusively

  1. Regional assignment of seven loci to 12p 13. 2-pter by PCR analysis of somatic cell hybrids containing the der(12) or the der(X) chromosome from a mesothelioma showing t(X; 12)(q22; p13)

    Energy Technology Data Exchange (ETDEWEB)

    Aerssens, J.; Chaffanet, M.; Baens, M.; Matthijs, G.; Van Den Berche, H.; Cassiman, J.J.; Marynen, P. (Arthritis and Metabolic Bone Disease Research Unit, Leuven (Belgium))

    1994-03-01

    Two somatic cell hybrids containing the der(12) or the der(X) from a mesothelioma with a translocation t(X;12) (q22;p13) as the only chromosomal change were generated to characterize the region of 12p12 containing the translocation breakpoint. Fluorescence in situ hybridization analysis showed the breakpoint on chromosome 12 to occur between VWF and D12S158. On the linkage map developed by J. Weissenbach et al., the breakpoints were located between DXS1106 and DCS1001 on chromosome X. PCR analysis based on genomic sequences, with DNA from both somatic cell hybrids, enabled mapping of CACNL1A1, FGF6, D12S370, D12S38OE, D12S381E, and D12S382E distally to the 12p13 breakpoint and to VWF. 11 refs., 2 figs., 1 tab.

  2. Viscous Flow over Nonlinearly Stretching Sheet with Effects of Viscous Dissipation

    Directory of Open Access Journals (Sweden)

    Javad Alinejad

    2012-01-01

    Full Text Available The flow and heat transfer characteristics of incompressible viscous flow over a nonlinearly stretching sheet with the presence of viscous dissipation is investigated numerically. The similarity transformation reduces the time-independent boundary layer equations for momentum and thermal energy into a set of coupled ordinary differential equations. The obtained equations, including nonlinear equation for the velocity field and differential equation by variable coefficient for the temperature field , are solved numerically by using the fourth order of Runge-Kutta integration scheme accompanied by shooting technique with Newton-Raphson iteration method. The effect of various values of Prandtl number, Eckert number and nonlinear stretching parameter are studied. The results presented graphically show some behaviors such as decrease in dimensionless temperature due to increase in Pr number, and curve relocations are observed when heat dissipation is considered.

  3. DNA analysis by single molecule stretching in nanofluidic biochips

    DEFF Research Database (Denmark)

    Abad, E.; Juarros, A.; Retolaza, A.

    2011-01-01

    Imprint Lithography (NIL) technology combined with a conventional anodic bonding of the silicon base and Pyrex cover. Using this chip, we have performed single molecule imaging on a bench-top fluorescent microscope system. Lambda phage DNA was used as a model sample to characterize the chip. Single molecules of λ-DNA......Stretching single DNA molecules by confinement in nanofluidic channels has attracted a great interest during the last few years as a DNA analysis tool. We have designed and fabricated a sealed micro/nanofluidic device for DNA stretching applications, based on the use of the high throughput Nano...... stained with the fluorescent dye YOYO-1 were stretched in the nanochannel array and the experimental results were analysed to determine the extension factor of the DNA in the chip and the geometrical average of the nanochannel inner diameter. The determination of the extension ratio of the chip provides...

  4. Cell volume and membrane stretch independently control K+ channel activity

    DEFF Research Database (Denmark)

    Bomholtz, Sofia Hammami; Willumsen, Niels J; Olsen, Hervør L

    2009-01-01

    A number of potassium channels including members of the KCNQ family and the Ca(2+) activated IK and SK, but not BK, are strongly and reversibly regulated by small changes in cell volume. It has been argued that this general regulation is mediated through sensitivity to changes in membrane stretch...... was not affected by membrane stretch. The results indicate that (1) activation of BK channels by local membrane stretch is not mimicked by membrane stress induced by cell swelling, and (2) activation of KCNQ1 channels by cell volume increase is not mediated by local tension in the cell membrane. We conclude....... To test this hypothesis we have studied the regulation of KCNQ1 and BK channels after expression in Xenopus oocytes. Results from cell-attached patch clamp studies (approximately 50 microm(2) macropatches) in oocytes expressing BK channels demonstrate that the macroscopic volume-insensitive BK current...

  5. Directional Cell Migration in Response to Repeated Substratum Stretching

    Science.gov (United States)

    Okimura, Chika; Iwadate, Yoshiaki

    2017-10-01

    Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

  6. Stretching of red blood cells at high strain rates

    Science.gov (United States)

    Mancuso, J. E.; Ristenpart, W. D.

    2017-10-01

    Most work on the mechanical behavior of red blood cells (RBCs) in flow has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this Rapid Communication, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that both the Kelvin-Voigt and Skalak viscoelastic models capture the observed stretching dynamics, up to strain rates as high as 2000 s-1. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques.

  7. Numerical and experimental investigation of stretch-flange forming

    International Nuclear Information System (INIS)

    Cinotti, N.; Shakeri, H.R.; Worswick, M.J.; Truttmann, S.; Finn, M.J.; Jain, M.; Lloyd, D.J.

    2000-01-01

    Simulations of stretch flange forming operations are undertaken using explicit dynamic finite element calculations incorporating anisotropic yield criteria. Simple circular stretch flanges utilizing a single circular punch to expand the cut-out were considered. Experiments were performed using 101mm diameter tooling on AA 5754 and AA 5182 aluminum alloy sheets, with varying cut-out and gauge size. Metallurgical aspects of the formability of these aluminum alloys and damage mechanisms were studied. Both optical and Scanning Electron Microscopy (SEM) were used to study ductile fracture behaviour in these materials during the forming operation. The limit strains obtained from the circular stretch flange formability experiments are compared to forming limit diagram (FLD) data from hemispherical dome specimens. (author)

  8. Investigating the role of musical genre in human perception of music stretching resistance

    OpenAIRE

    Chen, Jun; Wang, Chaokun

    2017-01-01

    To stretch a music piece to a given length is a common demand in people's daily lives, e.g., in audio-video synchronization and animation production. However, it is not always guaranteed that the stretched music piece is acceptable for general audience since music stretching suffers from people's perceptual artefacts. Over-stretching a music piece will make it uncomfortable for human psychoacoustic hearing. The research on music stretching resistance attempts to estimate the maximum stretchab...

  9. MODEL OF TECTONIC EARTHQUAKE PREPARATION AND OCCURRENCE AND ITS PRECURSORS IN CONDITIONS OF CRUSTAL STRETCHING

    Directory of Open Access Journals (Sweden)

    R. M. Semenov

    2018-01-01

    Full Text Available In connection with changes in the stress-strain state of the Earth's crust, various physical and mechanical processes, including destruction, take place in the rocks and are accompanied by tectonic earthquakes. Different models have been proposed to describe earthquake preparation and occurrence, depending on the mechanisms and the rates of geodynamic processes. One of the models considers crustal stretching that is characteristic of formation of rift structures. The model uses the data on rock samples that are stretched until destruction in a special laboratory installation. Based on the laboratory modeling, it is established that the samples are destroyed in stages that are interpreted as stages of preparation and occurrence of an earthquake source. The preparation stage of underground tremors is generally manifested by a variety of temporal (long-, medium- and short-term precursors. The main shortcoming of micro-modeling is that, considering small sizes of the investigated samples, it is impossible to reveal a link between the plastic extension of rocks (taking place in the earthquake hypocenter and the rock rupture. Plasticity is the ability of certain rocks to change shape and size irreversibly, while the rock continuity is maintained, in response to applied external forces. In order to take into account the effect of plastic deformation of rocks on earthquake preparation and occurrence, we propose not to refer to the diagrams showing stretching of the rock samples, but use a typical diagram of metal stretching, which can be obtained when testing a metal rod for breakage (Fig. 1. The diagram of metal stretching as a function of the relative elongation (to some degree of approximation and taking into account the coefficient of plasticity can be considered as a model of preparation and occurrence of an earthquake source in case of rifting. The energy released in the period immediately preceding the earthquake contributes to the emergence of

  10. A primary study on meridian-stretching of injected FDG using PET MPItool

    International Nuclear Information System (INIS)

    He Yijie; Tian Jiahe; Chen Yingmao; Yin Dayi; Zhang Jinming; Zhang Shuwen; Shao Mingzhe; Yao Shulin; Ding Weimin; Liu Zilai

    2002-01-01

    Objective: To show the images of tracer-stretching along the acupuncture meridian by use of PET with multipurpose imaging tool (MPItool's) fusion function. Methods: On 5 healthy volunteers, the authors measured the classical acupuncture points accurately with the biophysical measuring method. 18 F-fluorodeoxyglucose (FDG) was injected into the selected points, the others points along the same meridian were labelled with 18 F-FDG applied on the correspondent skin area of 2 . With the same body position, the transmission image and emission image was acquired respectively and fused with MPItool and its 3D display system. Results: The authors clearly showed not only the meridian-stretching images of the tracer, but also figured out the depth of the study points. The depth at SHANGJUXU point was about 3.8 cm and at ZUSANLI point was about 5,0 cm. The depths basically fit the classically documented ones of the correspondent acupuncture points. Conclusions: Using PET MPItool the authors preliminarily demonstrated that the tracer injected at the acupuncture point stretches along the correspondent meridian, and the depths of the meridian and the points (SHANGJUXU, ZUSANLI) detected are almost accordant with the classically documented ones

  11. Mechanical stretching of proteins-a theoretical survey of the Protein Data Bank

    International Nuclear Information System (INIS)

    Sulkowska, Joanna I; Cieplak, Marek

    2007-01-01

    The mechanical stretching of single proteins has been studied experimentally for about 50 proteins, yielding a variety of force patterns and peak forces. Here we perform a theoretical survey of proteins of known native structure and map out the landscape of possible dynamical behaviours under stretching at constant speed. We consider 7510 proteins comprising not more than 150 amino acids and 239 longer proteins. The model used is constructed based on the native geometry. It is solved by methods of molecular dynamics and validated by comparing the theoretical predictions to experimental results. We characterize the distribution of peak forces and investigate correlations with the system size and with the structure classification as characterized by the CATH scheme. Despite the presence of such correlations, proteins with the same CATH index may belong to different classes of dynamical behaviour. We identify proteins with the biggest forces and show that they belong to few topology classes. We determine which protein segments act as mechanical clamps and show that, in most cases, they correspond to long stretches of parallel β-strands, but other mechanisms are also possible. (topical review)

  12. Epithelial cell stretching and luminal acidification lead to a retarded development of stria vascularis and deafness in mice lacking pendrin.

    Directory of Open Access Journals (Sweden)

    Hyoung-Mi Kim

    2011-03-01

    Full Text Available Loss-of-function mutations of SLC26A4/pendrin are among the most prevalent causes of deafness. Deafness and vestibular dysfunction in the corresponding mouse model, Slc26a4(-/-, are associated with an enlargement and acidification of the membranous labyrinth. Here we relate the onset of expression of the HCO(3 (- transporter pendrin to the luminal pH and to enlargement-associated epithelial cell stretching. We determined expression with immunocytochemistry, cell stretching by digital morphometry and pH with double-barreled ion-selective electrodes. Pendrin was first expressed in the endolymphatic sac at embryonic day (E 11.5, in the cochlear hook-region at E13.5, in the utricle and saccule at E14.5, in ampullae at E16.5, and in the upper turn of the cochlea at E17.5. Epithelial cell stretching in Slc26a4(-/- mice began at E14.5. pH changes occurred first in the cochlea at E15.5 and in the endolymphatic sac at E17.5. At postnatal day 2, stria vascularis, outer sulcus and Reissner's membrane epithelial cells, and utricular and saccular transitional cells were stretched, whereas sensory cells in the cochlea, utricle and saccule did not differ between Slc26a4(+/- and Slc26a4(-/- mice. Structural development of stria vascularis, including vascularization, was retarded in Slc26a4(-/- mice. In conclusion, the data demonstrate that the enlargement and stretching of non-sensory epithelial cells precedes luminal acidification in the cochlea and the endolymphatic sac. Stretching and luminal acidification may alter cell-to-cell communication and lead to the observed retarded development of stria vascularis, which may be an important step on the path to deafness in Slc26a4(-/- mice, and possibly in humans, lacking functional pendrin expression.

  13. Dynamic Contractility and Efficiency Impairments in Stretch-Shortening Cycle Are Stretch-Load-Dependent After Training-Induced Muscle Damage

    NARCIS (Netherlands)

    Vaczi, Mark; Racz, Levente; Hortobagyi, Tibor; Tihanyi, Jozsef

    Vaczi, M, Racz, L, Hortobagyi, T, and Tihanyi, J. Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load-dependent after training-induced muscle damage. J Strength Cond Res 27(8): 2171-2179, 2013To determine the acute task and stretch-load dependency of

  14. Show-Bix &

    DEFF Research Database (Denmark)

    2014-01-01

    The anti-reenactment 'Show-Bix &' consists of 5 dias projectors, a dial phone, quintophonic sound, and interactive elements. A responsive interface will enable the Dias projectors to show copies of original dias slides from the Show-Bix piece ”March på Stedet”, 265 images in total. The copies are...

  15. Mechanical stretch increases CCN2/CTGF expression in anterior cruciate ligament-derived cells

    International Nuclear Information System (INIS)

    Miyake, Yoshiaki; Furumatsu, Takayuki; Kubota, Satoshi; Kawata, Kazumi; Ozaki, Toshifumi; Takigawa, Masaharu

    2011-01-01

    Highlights: → CCN2/CTGF localizes to the ligament-to-bone interface, but is not to the midsubstance region of human anterior cruciate ligament (ACL). → Mechanical stretch induces higher increase of CCN2/CTGF gene expression and protein secretion in ACL interface cells compared with ACL midsubstance cells. → CCN2/CTGF treatment stimulates the proliferation of ACL interface cells. -- Abstract: Anterior cruciate ligament (ACL)-to-bone interface serves to minimize the stress concentrations that would arise between two different tissues. Mechanical stretch plays an important role in maintaining cell-specific features by inducing CCN family 2/connective tissue growth factor (CCN2/CTGF). We previously reported that cyclic tensile strain (CTS) stimulates α1(I) collagen (COL1A1) expression in human ACL-derived cells. However, the biological function and stress-related response of CCN2/CTGF were still unclear in ACL fibroblasts. In the present study, CCN2/CTGF was observed in ACL-to-bone interface, but was not in the midsubstance region by immunohistochemical analyses. CTS treatments induced higher increase of CCN2/CTGF expression and secretion in interface cells compared with midsubstance cells. COL1A1 expression was not influenced by CCN2/CTGF treatment in interface cells despite CCN2/CTGF stimulated COL1A1 expression in midsubstance cells. However, CCN2/CTGF stimulated the proliferation of interface cells. Our results suggest that distinct biological function of stretch-induced CCN2/CTGF might regulate region-specific phenotypes of ACL-derived cells.

  16. Mechanical stretch increases CCN2/CTGF expression in anterior cruciate ligament-derived cells

    Energy Technology Data Exchange (ETDEWEB)

    Miyake, Yoshiaki [Department of Orthopaedic Surgery, Science of Functional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama (Japan); Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama (Japan); Furumatsu, Takayuki, E-mail: matino@md.okayama-u.ac.jp [Department of Orthopaedic Surgery, Science of Functional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama (Japan); Kubota, Satoshi; Kawata, Kazumi [Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama (Japan); Ozaki, Toshifumi [Department of Orthopaedic Surgery, Science of Functional Recovery and Reconstruction, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama (Japan); Takigawa, Masaharu [Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama (Japan)

    2011-06-03

    Highlights: {yields} CCN2/CTGF localizes to the ligament-to-bone interface, but is not to the midsubstance region of human anterior cruciate ligament (ACL). {yields} Mechanical stretch induces higher increase of CCN2/CTGF gene expression and protein secretion in ACL interface cells compared with ACL midsubstance cells. {yields} CCN2/CTGF treatment stimulates the proliferation of ACL interface cells. -- Abstract: Anterior cruciate ligament (ACL)-to-bone interface serves to minimize the stress concentrations that would arise between two different tissues. Mechanical stretch plays an important role in maintaining cell-specific features by inducing CCN family 2/connective tissue growth factor (CCN2/CTGF). We previously reported that cyclic tensile strain (CTS) stimulates {alpha}1(I) collagen (COL1A1) expression in human ACL-derived cells. However, the biological function and stress-related response of CCN2/CTGF were still unclear in ACL fibroblasts. In the present study, CCN2/CTGF was observed in ACL-to-bone interface, but was not in the midsubstance region by immunohistochemical analyses. CTS treatments induced higher increase of CCN2/CTGF expression and secretion in interface cells compared with midsubstance cells. COL1A1 expression was not influenced by CCN2/CTGF treatment in interface cells despite CCN2/CTGF stimulated COL1A1 expression in midsubstance cells. However, CCN2/CTGF stimulated the proliferation of interface cells. Our results suggest that distinct biological function of stretch-induced CCN2/CTGF might regulate region-specific phenotypes of ACL-derived cells.

  17. Localization and stretch-dependence of lung elastase activity in development and compensatory growth.

    Science.gov (United States)

    Young, Sarah Marie; Liu, Sheng; Joshi, Rashika; Batie, Matthew R; Kofron, Matthew; Guo, Jinbang; Woods, Jason C; Varisco, Brian Michael

    2015-04-01

    Synthesis and remodeling of the lung matrix is necessary for primary and compensatory lung growth. Because cyclic negative force is applied to developing lung tissue during the respiratory cycle, we hypothesized that stretch is a critical regulator of lung matrix remodeling. By using quantitative image analysis of whole-lung and whole-lobe elastin in situ zymography images, we demonstrated that elastase activity increased twofold during the alveolar stage of postnatal lung morphogenesis in the mouse. Remodeling was restricted to alveolar walls and ducts and was nearly absent in dense elastin band structures. In the mouse pneumonectomy model of compensatory lung growth, elastase activity increased threefold, peaking at 14 days postpneumonectomy and was higher in the accessory lobe compared with other lobes. Remodeling during normal development and during compensatory lung growth was different with increased major airway and pulmonary arterial remodeling during development but not regeneration, and with homogenous remodeling throughout the parenchyma during development, but increased remodeling only in subpleural regions during compensatory lung growth. Left lung wax plombage prevented increased lung elastin during compensatory lung growth. To test whether the adult lung retains an innate capacity to remodel elastin, we developed a confocal microscope-compatible stretching device. In ex vivo adult mouse lung sections, lung elastase activity increased exponentially with strain and in peripheral regions of lung more than in central regions. Our study demonstrates that lung elastase activity is stretch-dependent and supports a model in which externally applied forces influence the composition, structure, and function of the matrix during periods of alveolar septation. Copyright © 2015 the American Physiological Society.

  18. Cyclic mechanical stretch down-regulates cathelicidin antimicrobial peptide expression and activates a pro-inflammatory response in human bronchial epithelial cells

    Directory of Open Access Journals (Sweden)

    Harpa Karadottir

    2015-12-01

    Full Text Available Mechanical ventilation (MV of patients can cause damage to bronchoalveolar epithelium, leading to a sterile inflammatory response, infection and in severe cases sepsis. Limited knowledge is available on the effects of MV on the innate immune defense system in the human lung. In this study, we demonstrate that cyclic stretch of the human bronchial epithelial cell lines VA10 and BCi NS 1.1 leads to down-regulation of cathelicidin antimicrobial peptide (CAMP gene expression. We show that treatment of VA10 cells with vitamin D3 and/or 4-phenyl butyric acid counteracted cyclic stretch mediated down-regulation of CAMP mRNA and protein expression (LL-37. Further, we observed an increase in pro-inflammatory responses in the VA10 cell line subjected to cyclic stretch. The mRNA expression of the genes encoding pro-inflammatory cytokines IL-8 and IL-1β was increased after cyclic stretching, where as a decrease in gene expression of chemokines IP-10 and RANTES was observed. Cyclic stretch enhanced oxidative stress in the VA10 cells. The mRNA expression of toll-like receptor (TLR 3, TLR5 and TLR8 was reduced, while the gene expression of TLR2 was increased in VA10 cells after cyclic stretch. In conclusion, our in vitro results indicate that cyclic stretch may differentially modulate innate immunity by down-regulation of antimicrobial peptide expression and increase in pro-inflammatory responses.

  19. Dynamics of the OH stretching mode in crystalline Ba(ClO4)2.3H2O

    Science.gov (United States)

    Hutzler, Daniel; Brunner, Christian; Petkov, Petko St.; Heine, Thomas; Fischer, Sighart F.; Riedle, Eberhard; Kienberger, Reinhard; Iglev, Hristo

    2018-02-01

    The vibrational dynamics of the OH stretching mode in Ba(ClO4)2 trihydrate are investigated by means of femtosecond infrared spectroscopy. The sample offers plane cyclic water trimers in the solid phase that feature virtually no hydrogen bond interaction between the water molecules. Selective excitation of the symmetric and asymmetric stretching leads to fast population redistribution, while simultaneous excitation yields quantum beats, which are monitored via a combination tone that dominates the overtone spectrum. The combination of steady-state and time-resolved spectroscopy with quantum chemical simulations and general theoretical considerations gives indication of various aspects of symmetry breakage. The system shows a joint population lifetime of 8 ps and a long-lived coherence between symmetric and asymmetric stretching, which decays with a time constant of 0.6 ps.

  20. Dual solutions of three-dimensional flow and heat transfer over a non-linearly stretching/shrinking sheet

    Science.gov (United States)

    Naganthran, Kohilavani; Nazar, Roslinda; Pop, Ioan

    2018-05-01

    This study investigated the influence of the non-linearly stretching/shrinking sheet on the boundary layer flow and heat transfer. A proper similarity transformation simplified the system of partial differential equations into a system of ordinary differential equations. This system of similarity equations is then solved numerically by using the bvp4c function in the MATLAB software. The generated numerical results presented graphically and discussed in the relevance of the governing parameters. Dual solutions found as the sheet stretched and shrunk in the horizontal direction. Stability analysis showed that the first solution is physically realizable whereas the second solution is not practicable.

  1. Cyclic Mechanical Stretch Up-regulates Hepatoma-Derived Growth Factor Expression in Cultured Rat Aortic Smooth Muscle Cells.

    Science.gov (United States)

    Kao, Ying-Hsien; Chen, Po-Han; Sun, Cheuk-Kwan; Chang, Yo-Chen; Lin, Yu-Chun; Tsai, Ming-Shian; Lee, Po-Huang; Cheng, Cheng-I

    2018-02-21

    Hepatoma-derived growth factor (HDGF) is a potent mitogen for vascular smooth muscle cells (SMCs) during embryogenesis and injury repair of vessel walls. Whether mechanical stimuli modulate HDGF expression remains unknown. This study aimed at investigating whether cyclic mechanical stretch plays a regulatory role in HDGF expression and regenerative cytokine production in aortic SMCs. A SMC cell line was grown on a silicone-based elastomer chamber with extracellular matrix coatings (either type I collagen or fibronectin) and received cyclic and uni-axial mechanical stretches with 10% deformation at frequency 1 Hz. Morphological observation showed that fibronectin coating provided better cell adhesion and spreading and that consecutive 6 hours of cyclic mechanical stretch remarkably induced reorientation and realignment of SMCs. Western blotting detection demonstrated that continuous mechanical stimuli elicited up-regulation of HDGF and PCNA, a cell proliferative marker. Signal kinetic profiling study indicated that cyclic mechanical stretch induced signaling activity in RhoA/ROCK and PI3K/Akt cascades. Kinase inhibition study further showed that blockade of PI3K activity suppressed the stretch-induced TNF-a, whereas RhoA/ROCK inhibition significantly blunted the IL-6 production and HDGF over-expression. Moreover, siRNA-mediated HDGF gene silencing significantly suppressed constitutive expression of IL-6, but not TNF-α, in SMCs. These findings support the role of HDGF in maintaining vascular expression of IL-6, which has been regarded a crucial regenerative factor for acute vascular injury. In conclusion, cyclic mechanical stretch may maintain constitutive expression of HDGF in vascular walls and be regarded an important biophysical regulator in vascular regeneration. ©2018 The Author(s).

  2. Optimal design of tunable phononic bandgap plates under equibiaxial stretch

    International Nuclear Information System (INIS)

    Hedayatrasa, Saeid; Abhary, Kazem; Uddin, M S; Guest, James K

    2016-01-01

    Design and application of phononic crystal (PhCr) acoustic metamaterials has been a topic with tremendous growth of interest in the last decade due to their promising capabilities to manipulate acoustic and elastodynamic waves. Phononic controllability of waves through a particular PhCr is limited only to the spectrums located within its fixed bandgap frequency. Hence the ability to tune a PhCr is desired to add functionality over its variable bandgap frequency or for switchability. Deformation induced bandgap tunability of elastomeric PhCr solids and plates with prescribed topology have been studied by other researchers. Principally the internal stress state and distorted geometry of a deformed phononic crystal plate (PhP) changes its effective stiffness and leads to deformation induced tunability of resultant modal band structure. Thus the microstructural topology of a PhP can be altered so that specific tunability features are met through prescribed deformation. In the present study novel tunable PhPs of this kind with optimized bandgap efficiency-tunability of guided waves are computationally explored and evaluated. Low loss transmission of guided waves throughout thin walled structures makes them ideal for fabrication of low loss ultrasound devices and structural health monitoring purposes. Various tunability targets are defined to enhance or degrade complete bandgaps of plate waves through macroscopic tensile deformation. Elastomeric hyperelastic material is considered which enables recoverable micromechanical deformation under tuning finite stretch. Phononic tunability through stable deformation of phononic lattice is specifically required and so any topology showing buckling instability under assumed deformation is disregarded. Nondominated sorting genetic algorithm (GA) NSGA-II is adopted for evolutionary multiobjective topology optimization of hypothesized tunable PhP with square symmetric unit-cell and relevant topologies are analyzed through finite

  3. EFFICACY OF CYRIAX PHYSIOTHERAPY VERSUS ECCENTRIC STRENGTHENING AND STRETCHING EXERCISES IN CHRONIC LATERAL EPICONDYLITIS PATIENTS

    Directory of Open Access Journals (Sweden)

    Madhusmita Koch

    2015-10-01

    Full Text Available Background: Lateral Epicondylitis is the most common lesion of the elbow, affecting the tendinous origin of the wrist extensors. Although conservative treatment of this condition has been the subject of numerous studies, there is no agreement as to the most effective management strategy. Therefore, this study was designed to compare the efficacy of Cyriax physiotherapy Versus Eccentric Strengthening and Stretching exercises in reducing the pain and improving the grip strength and functional status of the affected extremity in chronic lateral epicondylitis. Method: An experimental study design, 60 subjects meeting the inclusion criteria were selected for the study and were randomly assigned into two groups: Group A (N=30 received Cyriax Physiotherapy and Group B(N=30 received Eccentric strengthening and static stretching of Extensor Carpi Radialis Brevis. Low Level Laser Therapy was a common treatment for both the groups. After 4 weeks of treatment, assessment was performed using Visual Analogue Scale (VAS, Hand Held Dynamometer (HHD and Patient Rated Tennis Elbow Evaluation Questionnaire (PRTEE at 0 week and at the end of 4 weeks. Results: Data analysis revealed that there is no statistically significant difference between the groups in VAS, HHD and PRTEE scores i.e. average improvement post treatment in both the groups are equal, but within group comparisons showed significant improvements in both the groups. Conclusion: The efficacy of Cyriax Physiotherapy is equal to Eccentric Strengthening and Stretching Exercises in chronic lateral epicondylitis.

  4. Stretched inverse opal colloid crystal substrates-induced orientation of fibroblast

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y C; Tang, Z M; Feng, Z Q; Xie, Z Y; Gu, Z Z, E-mail: gu@seu.edu.c [State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096 (China)

    2010-06-01

    Recently, there has been increasing interest in studying the interaction between mammalian cells and nanometer-sized structures. However, the effect of nanostructures on cell behavior, such as cell morphology and alignment, is still largely unknown. Inverse opal colloid crystal substrates, which can be stretched to produce nano-scale pore structures of different degrees of orientation, serve as a convenient model system to study the effect of nanotopography on cell morphology and cell alignment. In this work, we fabricated inverse opal colloidal crystal films that were either unstretched or stretched to three, four or six times their original length, producing pore structures of increasing degree of orientation. Human dermal fibroblast-fetal (HDF-f) cells were seeded and cultured on these four types of substrates. The results from fluorescence microscopy and scanning electron microscopy indicated that cells showed the highest degree of alignment when cultured on inverse opal colloid crystal films that were stretched the most (six times original length). The results also demonstrated that the orientation of nanostructures could affect both the morphology and growth direction of fibroblasts. The ability to control the direction of cell growth through the engineering of nanostructures could have important applications in tissue engineering, especially for tissues with anisotropic structures, such as cardiac muscle, blood vessel, tendon and ligament.

  5. Stretched inverse opal colloid crystal substrates-induced orientation of fibroblast

    International Nuclear Information System (INIS)

    Wang, Y C; Tang, Z M; Feng, Z Q; Xie, Z Y; Gu, Z Z

    2010-01-01

    Recently, there has been increasing interest in studying the interaction between mammalian cells and nanometer-sized structures. However, the effect of nanostructures on cell behavior, such as cell morphology and alignment, is still largely unknown. Inverse opal colloid crystal substrates, which can be stretched to produce nano-scale pore structures of different degrees of orientation, serve as a convenient model system to study the effect of nanotopography on cell morphology and cell alignment. In this work, we fabricated inverse opal colloidal crystal films that were either unstretched or stretched to three, four or six times their original length, producing pore structures of increasing degree of orientation. Human dermal fibroblast-fetal (HDF-f) cells were seeded and cultured on these four types of substrates. The results from fluorescence microscopy and scanning electron microscopy indicated that cells showed the highest degree of alignment when cultured on inverse opal colloid crystal films that were stretched the most (six times original length). The results also demonstrated that the orientation of nanostructures could affect both the morphology and growth direction of fibroblasts. The ability to control the direction of cell growth through the engineering of nanostructures could have important applications in tissue engineering, especially for tissues with anisotropic structures, such as cardiac muscle, blood vessel, tendon and ligament.

  6. Stretched exponential distributions in nature and economy: ``fat tails'' with characteristic scales

    Science.gov (United States)

    Laherrère, J.; Sornette, D.

    1998-04-01

    To account quantitatively for many reported "natural" fat tail distributions in Nature and Economy, we propose the stretched exponential family as a complement to the often used power law distributions. It has many advantages, among which to be economical with only two adjustable parameters with clear physical interpretation. Furthermore, it derives from a simple and generic mechanism in terms of multiplicative processes. We show that stretched exponentials describe very well the distributions of radio and light emissions from galaxies, of US GOM OCS oilfield reserve sizes, of World, US and French agglomeration sizes, of country population sizes, of daily Forex US-Mark and Franc-Mark price variations, of Vostok (near the south pole) temperature variations over the last 400 000 years, of the Raup-Sepkoski's kill curve and of citations of the most cited physicists in the world. We also discuss its potential for the distribution of earthquake sizes and fault displacements. We suggest physical interpretations of the parameters and provide a short toolkit of the statistical properties of the stretched exponentials. We also provide a comparison with other distributions, such as the shifted linear fractal, the log-normal and the recently introduced parabolic fractal distributions.

  7. Acute effect of passive rest intervals and stretching exercise on multiple set performance

    Directory of Open Access Journals (Sweden)

    Antonio Claudio do Rosário Souza

    2009-01-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2009v11n4p435 The objective of this study was to determine the acute effect of passive rest intervals and static stretching between resistance exercise sets on the number of maximal repetitions (RM, rating of perceived exertion (RPE, and cumulative number of repetitions in multiple sets with a workload adjusted by the 8RM test. Fourteen trained male subjects (24.4 ± 2.1 years; 79.1 ± 7.1 kg; 175.4 ± 5.6 cm were studied. On the first two visits, the subjects were submitted to the test and 8RM re-test using chest press (CP and squat (SQ exercises. On the two subsequent visits, all subjects were randomly assigned to two experimental situations: a 8RM test with a passive rest interval (PI; b 8RM test with static stretching (SS. The subjects performed three sets of CP and SQ, intercalated with 2 minutes of passive rest or 30 seconds of static stretching. ANOVA revealed a significant decrease (p < 0.05 in the second (PI = 6 ± 0.8 x SS = 5.2 ± 1.0 repetitions and third (PI = 4.1 ± 0.8 X SS = 3.3 ± 0.6 repetitions sets for CP and only in the third set (PI = 4.9 ± 0.8 X SS = 4.2 ± 1.0 repetitions for SQ. For RPE, the Wilcoxon test showed significant differences (p < 0.05 between all sets for CP and SQ. For the cumulative number of repetitions, the paired t-test revealed a significant decrease (p < 0.05 for CP (PI = 18.3 ± 1.5 X SS = 16.8 ± 1.6 repetitions. These results indicate that static stretching between resistance exercise sets decreases 8RM test performance.

  8. EFFECTIVENESS OF INSTUMENTAL ASSISTED SOFT TISSUE MOBILIZATION TECHNIQUE WITH STATIC STRETCHING IN SUBJECTS WITH PLANTAR FASCIITIS

    Directory of Open Access Journals (Sweden)

    Vinod Babu. K

    2014-08-01

    Full Text Available Background: Instrumental assisted soft tissue mobilization and static stretching found to be effective in plantar fasciitis, however the combined effectiveness of these techniques were unknown. The purpose of this study is to find the effect of Instrumental assisted soft tissue mobilization technique for plantar fascia combined with static stretching of triceps surae for subjects with chronic stage of Plantar Fasciitis on pain intensity, ankle dorsiflexion range of motion and functional disability. Methods: An experimental study design, selected subjects with chronic Plantar Fasciitis randomized subjects into each Study and Control group. Total of 40 subject’s data who completed study, 20 in each group, was used for analysis. Control group received conventional exercise while Study group received conventional exercises with Instrumental assisted soft tissue mobilization combined with static stretching of triceps surae muscle. Outcome measurements such as Intensity of pain using Numerical Pain Rating Scale-101 (NPRS-101, function disability using Foot Function Index Pain Subscale (FFI and ankle dorsiflexion active range of motion using Goniometer was measured before and after 2 weeks of intervention. Results: There is statistically significant improvement in means of NRS-101, ankle dorsiflexion active range of motion and Foot Function Index Pain Subscale after intervention in both groups. When the post-intervention means were compared between Study and Control group after 2 weeks of treatment there is statistically significant difference in means between the groups whereas study group showed greater percentage of improvement than control group. Conclusion: It is concluded that Instrumental assisted soft tissue mobilization technique combined with static stretching of triceps surae muscle is significantly effective than conventional exercises on reducing pain, improving ankle dorsiflexion range of motion and functional disability for subjects

  9. Entropy generation in MHD flow of a uniformly stretched vertical ...

    African Journals Online (AJOL)

    This paper reports the analytical calculation of the entropy generation due to heat and mass transfer and fluid friction in steady state of a uniformly stretched vertical permeable surface with heat and mass diffusive walls, by solving analytically the mass, momentum, species concentration and energy balance equation, using ...

  10. Effect of Mechanical Stretching of the Skin on Collagen Fibril ...

    African Journals Online (AJOL)

    Stabilization of collagen fibres during development and through growth to maturation has now become fairly documented. In vitro effect of mechanical stretching of ratsf skin on oxidative deamination of ε-NH2-groups of lysine and hydroxylysine, and functional properties of its type . collagen were studied. Experiments were ...

  11. Flow of viscous fluid along an exponentially stretching curved surface

    Directory of Open Access Journals (Sweden)

    N.F. Okechi

    Full Text Available In this paper, we present the boundary layer analysis of flow induced by rapidly stretching curved surface with exponential velocity. The governing boundary value problem is reduced into self-similar form using a new similarity transformation. The resulting equations are solved numerically using shooting and Runge-Kutta methods. The numerical results depicts that the fluid velocity as well as the skin friction coefficient increases with the surface curvature, similar trend is also observed for the pressure. The dimensionless wall shear stress defined for this problem is greater than that of a linearly stretching curved surface, but becomes comparably less for a surface stretching with a power-law velocity. In addition, the result for the plane surface is a special case of this study when the radius of curvature of the surface is sufficiently large. The numerical investigations presented in terms of the graphs are interpreted with the help of underlying physics of the fluid flow and the consequences arising from the curved geometry. Keywords: Boundary layer flow, Curved surface, Exponential stretching, Curvature

  12. Contact of a spherical probe with a stretched rubber substrate

    Science.gov (United States)

    Frétigny, Christian; Chateauminois, Antoine

    2017-07-01

    We report on a theoretical and experimental investigation of the normal contact of stretched neo-Hookean substrates with rigid spherical probes. Starting from a published formulation of surface Green's function for incremental displacements on a prestretched, neo-Hookean, substrate [J. Mech. Phys. Solids 56, 2957 (2008), 10.1016/j.jmps.2008.07.002], a model is derived for both adhesive and nonadhesive contacts. The shape of the elliptical contact area together with the contact load and the contact stiffness are predicted as a function of the in-plane stretch ratios λx and λy of the substrate. The validity of this model is assessed by contact experiments carried out using an uniaxally stretched silicone rubber. For stretch ratio below about 1.25, a good agreement is observed between theory and experiments. Above this threshold, some deviations from the theoretical predictions are induced as a result of the departure of the mechanical response of the silicone rubber from the neo-Hokeean description embedded in the model.

  13. Sport stretching : Effect on passive muscle stiffness of short hamstrings

    NARCIS (Netherlands)

    Halbertsma, JPK; vanBolhuis, AI; Goeken, LNH

    Objective: To evaluate the effects of one 10-minute stretch on muscle stiffness in subjects with short hamstrings. Design: Randomized control trial. Setting: Laboratory for human movement sciences in the department of rehabilitation of a university hospital. Subjects: Sixteen students from the

  14. Automation of a single-DNA molecule stretching device

    DEFF Research Database (Denmark)

    Sørensen, Kristian Tølbøl; Lopacinska, Joanna M.; Tommerup, Niels

    2015-01-01

    We automate the manipulation of genomic-length DNA in a nanofluidic device based on real-time analysis of fluorescence images. In our protocol, individual molecules are picked from a microchannel and stretched with pN forces using pressure driven flows. The millimeter-long DNA fragments free...

  15. Measuring the curvature of space with stretched strings

    International Nuclear Information System (INIS)

    Lyth, D.H.

    1983-01-01

    The equilibrium of a stretched string in curved space is studied. The problem is first formulated without detailed assumptions, then the force of gravity on the string is calculated from general relativity with a static metric. Apart from the latter calculation everything is done in ordinary space rather than in space-time. A number of simple cases are worked out explicitly. (author)

  16. A Japanese Stretching Intervention Can Modify Lumbar Lordosis Curvature

    NARCIS (Netherlands)

    Kadono, Norio; Tsuchiya, Kazushi; Uematsu, Azusa; Kamoshita, Hiroshi; Kiryu, Kazunori; Hortobagyi, Tibor; Suzuki, Shuji

    Study Design: Eighteen healthy male adults were assigned to either an intervention or control group. Objectives: Isogai dynamic therapy (IDT) is one of Japanese stretching interventions and has been practiced for over 70 years. However, its scientific quantitative evidence remains unestablished. The

  17. Mediators of Yoga and Stretching for Chronic Low Back Pain

    Directory of Open Access Journals (Sweden)

    Karen J. Sherman

    2013-01-01

    Full Text Available Although yoga is an effective treatment for chronic low back pain, little is known about the mechanisms responsible for its benefits. In a trial comparing yoga to intensive stretching and self-care, we explored whether physical (hours of back exercise/week, cognitive (fear avoidance, body awareness, and self-efficacy, affective (psychological distress, perceived stress, positive states of mind, and sleep, and physiological factors (cortisol, DHEA mediated the effects of yoga or stretching on back-related dysfunction (Roland-Morris Disability Scale (RDQ. For yoga, 36% of the effect on 12-week RDQ was mediated by increased self-efficacy, 18% by sleep disturbance, 9% by hours of back exercise, and 61% by the best combination of all possible mediators (6 mediators. For stretching, 23% of the effect was mediated by increased self-efficacy, 14% by days of back exercise, and 50% by the best combination of all possible mediators (7 mediators. In open-ended questions, ≥20% of participants noted the following treatment benefits: learning new exercises (both groups, relaxation, increased awareness, and the benefits of breathing (yoga, benefits of regular practice (stretching. Although both self-efficacy and hours of back exercise were the strongest mediators for each intervention, compared to self-care, qualitative data suggest that they may exert their benefits through partially distinct mechanisms.

  18. OH stretching frequencies in systems with intramolecular hydrogen bonds

    DEFF Research Database (Denmark)

    Spanget-Larsen, Jens; Hansen, Bjarke Knud Vilster; Hansen, Poul Erik

    2011-01-01

    OH stretching wavenumbers were investigated for 30 species with intramolecularly hydrogen bonded hydroxyl groups, covering the range from 3600 to ca. 1900 cm-1. Theoretical wavenumbers were predicted with B3LYP/6-31G(d) density functional theory using the standard harmonic approximation, as well...

  19. Transient filament stretching rheometer I: force balance analysis

    DEFF Research Database (Denmark)

    Szabo, Peter

    1997-01-01

    The filament stretching device which is used increasingly as an apparatus for measuring extensional properties of polymeric liquids isanalysed. A force balance that includes the effects of inertia and surface tension is derived.The force balance may be used to correct for the effects of inertia...

  20. Acute effects of active isolated stretching on vertical jump ...

    African Journals Online (AJOL)

    The purpose of the study was to determine the acute effects of active isolated stretching on muscular peak power production. Sixty healthy, physically active volunteers (aged 18-28) participated as subjects in this study. Subjects were randomly assigned to two groups; the control group and the experimental group. Subjects ...

  1. On zero variance Monte Carlo path-stretching schemes

    International Nuclear Information System (INIS)

    Lux, I.

    1983-01-01

    A zero variance path-stretching biasing scheme proposed for a special case by Dwivedi is derived in full generality. The procedure turns out to be the generalization of the exponential transform. It is shown that the biased game can be interpreted as an analog simulation procedure, thus saving some computational effort in comparison with the corresponding nonanalog game

  2. Effect of hexane treatment and uniaxial stretching on bending ...

    African Journals Online (AJOL)

    PVDF) film was studied. The quantity, β31, defined as the bending piezoelectric stress constant, was calculated. After hexane treatment and uniaxial stretching of the PVDF film, the value of β31 was 5.75 mV/m and 8.00 mV/m for draw ratio of ...

  3. The health of benthic diatom assemblages in lower stretch

    Indian Academy of Sciences (India)

    This study examines the ecological state of epilithic diatom assemblages along the lower stretch of Mandakini, a glacier-fed Himalayan river. The diatoms were sampled at four stations during winter and summer, only once in each season. Valve counts were obtained from Naphrax mounts prepared from each sample.

  4. MHD flow of a uniformly stretched vertical permeable membrane in ...

    African Journals Online (AJOL)

    We present a magneto - hydrodynamic flow of a uniformly stretched vertical permeable surface undergoing Arrhenius heat reaction. The analytical solutions are obtained for concentration, temperature and velocity fields using an asymptotic approximation, similar to that of Ayeni et al 2004. It is shown that the temperature ...

  5. A single molecule DNA flow stretching microscope for undergraduates

    NARCIS (Netherlands)

    Williams, Kelly; Grafe, Brendan; Burke, Kathryn M.; Tanner, Nathan; van Oijen, Antoine M.; Loparo, Joseph; Price, Allen C.

    2011-01-01

    The design of a simple, safe, and inexpensive single molecule flow stretching instrument is presented. The instrument uses a low cost upright microscope coupled to a webcam for imaging single DNA molecules that are tethered in an easy to construct microfluidic flow cell. The system requires no

  6. METODE ACTIVE ISOLATED STRETCHING (AIS DAN METODE HOLD RELAX STRETCHING (HRS SAMA EFEKTIF DALAM MENINGKATKAN FLEKSIBILITAS OTOT HAMSTRING PADA MAHASISWA AKADEMI FISIOTERAPI WIDYA HUSADA SEMARANG YANG MENGALAMI HAMSTRING MUSCLE TIGHTNESS (HMTs

    Directory of Open Access Journals (Sweden)

    Akhmad alfajri

    2015-08-01

    Full Text Available Students with Hamstring Muscle Tightness (HMTs will be at risk of Anterior Crusiatum Ligament (ACL, Low Back Pain (LBP and also Plantar Faciitis. One of the efforts to reduce tightness and improve hamstring muscle flexibility is stretching. Active Isolated Stretching (AIS and Hold Relax Stretching (HRS are the methods of influential stretching to improve muscle flexibility. The goal of the research is to prove that AIS method is equally effective with the HRS method to improve hamstring muscle flexibility to the HMTs patients. The research method was true experimental with pre and post test group design. The research was conducted for 3 weeks and the samples are 23 students in range of 18-25 years old students of physical therapy in Physical Therapy Academy of Widya Husada Semarang which divided into 2 groups; AIS group (n= 12 and HRS group (n= 11. The research used Sit and Reach Test (SRT as the measurement instrument. The result of the research was the average result of AIS group used SRT before treatment was 1.75 cm, SB= 4.309 and after treatment was 10. 58 cm, SB = 8. 005 within p= 0.000 (p 0.05. Those explain that the improvement of hamstring muscle flexibility to the two groups does not show any significant difference. Conclusion from this study was active isolated stretching method and hold relax stretching method are equally effective to improving muscle flexibility of hamstring muscle tightness students of physical therapy in Physical Therapy Academy of Widya Husada Semarang.

  7. Force encoding in muscle spindles during stretch of passive muscle.

    Directory of Open Access Journals (Sweden)

    Kyle P Blum

    2017-09-01

    Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

  8. Force encoding in muscle spindles during stretch of passive muscle.

    Science.gov (United States)

    Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

    2017-09-01

    Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

  9. Immediate effects of different types of stretching exercises on badminton jump smash.

    Science.gov (United States)

    Jang, Hwi S; Kim, Daeho; Park, Jihong

    2018-01-01

    Since different types of stretching exercises may alter athletic performance, we compared the effects of three types of stretching exercises on badminton jump smash. Sixteen male collegiate badminton players performed one of three different stretching exercises in a counterbalanced order on different days. Static stretching had seven typical stretches, while dynamic stretching involved nine dynamic movements, and resistance dynamic stretching was performed with weighted vests and dumbbells. Before and after each stretching exercise, subjects performed 20 trials of jump smashes. Dependent measurements were the jump heights during jump smashes, velocities of jump-smashed shuttlecocks, and drop point of jump-smashed shuttlecocks. To test the effects of each stretching exercise, we performed mixed model ANOVAs and calculated between-time effect sizes (ES). Each stretching exercise improved the jump heights during jump smashes (type main effect: F(2,75)=1.19, P=0.31; static stretching: 22.1%, Pjump-smashed shuttlecocks (type main effect: F(2,75)=2.18, P=0.12; static stretching: 5.7%, P=0.61, ES=0.39; dynamic stretching: 3.4%, P=0.94, ES=0.28; resistance dynamic stretching: 6%, P=0.50, ES=0.66). However, there were no differences among the stretching exercises for any measurement. The drop point of jump-smashed shuttlecocks did not change (interaction: F(2,75)=0.88, P=0.42). All stretching exercises improved badminton jump smash performance, but we could not determine the best protocol. Since badminton requires high-speed movement and explosive force, we suggest performing dynamic stretching or resistance dynamic stretching.

  10. Talking with TV shows

    DEFF Research Database (Denmark)

    Sandvik, Kjetil; Laursen, Ditte

    2014-01-01

    User interaction with radio and television programmes is not a new thing. However, with new cross-media production concepts such as X Factor and Voice, this is changing dramatically. The second-screen logic of these productions encourages viewers, along with TV’s traditional one-way communication...... mode, to communicate on interactive (dialogue-enabling) devices such as laptops, smartphones and tablets. Using the TV show Voice as our example, this article shows how the technological and situational set-up of the production invites viewers to engage in new ways of interaction and communication...

  11. Talk Show Science.

    Science.gov (United States)

    Moore, Mitzi Ruth

    1992-01-01

    Proposes having students perform skits in which they play the roles of the science concepts they are trying to understand. Provides the dialog for a skit in which hot and cold gas molecules are interviewed on a talk show to study how these properties affect wind, rain, and other weather phenomena. (MDH)

  12. Obesity in show cats.

    Science.gov (United States)

    Corbee, R J

    2014-12-01

    Obesity is an important disease with a high prevalence in cats. Because obesity is related to several other diseases, it is important to identify the population at risk. Several risk factors for obesity have been described in the literature. A higher incidence of obesity in certain cat breeds has been suggested. The aim of this study was to determine whether obesity occurs more often in certain breeds. The second aim was to relate the increased prevalence of obesity in certain breeds to the official standards of that breed. To this end, 268 cats of 22 different breeds investigated by determining their body condition score (BCS) on a nine-point scale by inspection and palpation, at two different cat shows. Overall, 45.5% of the show cats had a BCS > 5, and 4.5% of the show cats had a BCS > 7. There were significant differences between breeds, which could be related to the breed standards. Most overweight and obese cats were in the neutered group. It warrants firm discussions with breeders and cat show judges to come to different interpretations of the standards in order to prevent overweight conditions in certain breeds from being the standard of beauty. Neutering predisposes for obesity and requires early nutritional intervention to prevent obese conditions. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

  13. Honored Teacher Shows Commitment.

    Science.gov (United States)

    Ratte, Kathy

    1987-01-01

    Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)

  14. The energy show

    International Nuclear Information System (INIS)

    1988-01-01

    The Energy Show is a new look at the problems of world energy, where our supplies come from, now and in the future. The programme looks at how we need energy to maintain our standards of living. Energy supply is shown as the complicated set of problems it is - that Fossil Fuels are both raw materials and energy sources, that some 'alternatives' so readily suggested as practical options are in reality a long way from being effective. (author)

  15. History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

    Science.gov (United States)

    Stubbs, Peter W; Walsh, Lee D; D'Souza, Arkiev; Héroux, Martin E; Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

    2018-06-01

    In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the

  16. GNG Motifs Can Replace a GGG Stretch during G-Quadruplex Formation in a Context Dependent Manner.

    Directory of Open Access Journals (Sweden)

    Kohal Das

    Full Text Available G-quadruplexes are one of the most commonly studied non-B DNA structures. Generally, these structures are formed using a minimum of 4, three guanine tracts, with connecting loops ranging from one to seven. Recent studies have reported deviation from this general convention. One such deviation is the involvement of bulges in the guanine tracts. In this study, guanines along with bulges, also referred to as GNG motifs have been extensively studied using recently reported HOX11 breakpoint fragile region I as a model template. By strategic mutagenesis approach we show that the contribution from continuous G-tracts may be dispensible during G-quadruplex formation when such motifs are flanked by GNGs. Importantly, the positioning and number of GNG/GNGNG can also influence the formation of G-quadruplexes. Further, we assessed three genomic regions from HIF1 alpha, VEGF and SHOX gene for G-quadruplex formation using GNG motifs. We show that HIF1 alpha sequence harbouring GNG motifs can fold into intramolecular G-quadruplex. In contrast, GNG motifs in mutant VEGF sequence could not participate in structure formation, suggesting that the usage of GNG is context dependent. Importantly, we show that when two continuous stretches of guanines are flanked by two independent GNG motifs in a naturally occurring sequence (SHOX, it can fold into an intramolecular G-quadruplex. Finally, we show the specific binding of G-quadruplex binding protein, Nucleolin and G-quadruplex antibody, BG4 to SHOX G-quadruplex. Overall, our study provides novel insights into the role of GNG motifs in G-quadruplex structure formation which may have both physiological and pathological implications.

  17. Interset stretching does not influence the kinematic profile of consecutive bench-press sets.

    Science.gov (United States)

    García-López, David; Izquierdo, Mikel; Rodríguez, Sergio; González-Calvo, Gustavo; Sainz, Nuria; Abadía, Olaia; Herrero, Azael J

    2010-05-01

    This study was undertaken to examine the role of interset stretching on the time course of acceleration portion AP and mean velocity profile during the concentric phase of 2 bench-press sets with a submaximal load (60% of the 1 repetition maximum). Twenty-five college students carried out, in 3 different days, 2 consecutive bench-press sets leading to failure, performing between sets static stretching, ballistic stretching, or no stretching. Acceleration portion and lifting velocity patterns of the concentric phase were not altered during the second set, regardless of the stretching treatment performed. However, when velocity was expressed in absolute terms, static stretching reduced significantly (p velocity during the second set compared to the first one. Therefore, if maintenance of a high absolute velocity over consecutive sets is important for training-related adaptations, static stretching should be avoided or replaced by ballistic stretching.

  18. On MHD nonlinear stretching flow of Powell–Eyring nanomaterial

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    Full Text Available This communication addresses the magnetohydrodynamic (MHD flow of Powell–Eyring nanomaterial bounded by a nonlinear stretching sheet. Novel features regarding thermophoresis and Brownian motion are taken into consideration. Powell–Eyring fluid is electrically conducted subject to non-uniform applied magnetic field. Assumptions of small magnetic Reynolds number and boundary layer approximation are employed in the mathematical development. Zero nanoparticles mass flux condition at the sheet is selected. Adequate transformation yield nonlinear ordinary differential systems. The developed nonlinear systems have been computed through the homotopic approach. Effects of different pertinent parameters on velocity, temperature and concentration fields are studied and analyzed. Further numerical data of skin friction and heat transfer rate is also tabulated and interpreted. Keywords: Powell–Eyring fluid, Magnetohydrodynamics, Nanomaterial, Nonlinear stretching surface

  19. FUZZY BASED CONTRAST STRETCHING FOR MEDICAL IMAGE ENHANCEMENT

    Directory of Open Access Journals (Sweden)

    T.C. Raja Kumar

    2011-07-01

    Full Text Available Contrast Stretching is an important part in medical image processing applications. Contrast is the difference between two adjacent pixels. Fuzzy statistical values are analyzed and better results are produced in the spatial domain of the input image. The histogram mapping produces the resultant image with less impulsive noise and smooth nature. The probabilities of gray values are generated and the fuzzy set is determined from the position of the input image pixel. The result indicates the good performance of the proposed fuzzy based stretching. The inverse transform of the real values are mapped with the input image to generate the fuzzy statistics. This approach gives a flexible image enhancement for medical images in the presence of noises.

  20. An economical analysis of stretch-out for Angra 1

    International Nuclear Information System (INIS)

    Sakai, M.; Mascarenhas, H.A.

    1990-01-01

    An economical assessment of Angra 1 fuel cycle stretch-out is performed by means of NUCOST 1.0, a PWR power cost calculation code. International basic costs and an interest rate of 10%a were utilized. During the natural part of the fuel cycle an hypothetical capacity factor of 70% and in the stretch-out part a decrease in Plant's thermal efficiency have also been taken into account. The neutronic data were generated by FASER, MULTIMEDIUM, MEDIUM and PINPOW code system, simulating Angra 1 in the CAOC (constant Axial-Offset Control) operation. Assumming no proplems in the Plant's strecth-out phase, an optimum extension pont of 1 MWd/kg would be attained, what affords an US$700,000 savings by cycle when fuel and operation and maintenance costs are considered. (author) [pt

  1. Showing Value (Editorial

    Directory of Open Access Journals (Sweden)

    Denise Koufogiannakis

    2009-06-01

    Full Text Available When Su Cleyle and I first decided to start Evidence Based Library and Information Practice, one of the things we agreed upon immediately was that the journal be open access. We knew that a major obstacle to librarians using the research literature was that they did not have access to the research literature. Although Su and I are both academic librarians who can access a wide variety of library and information literature from our institutions, we belong to a profession where not everyone has equal access to the research in our field. Without such access to our own body of literature, how can we ever hope for practitioners to use research evidence in their decision making? It would have been contradictory to the principles of evidence based library and information practice to do otherwise.One of the specific groups we thought could use such an open access venue for discovering research literature was school librarians. School librarians are often isolated and lacking access to the research literature that may help them prove to stakeholders the importance of their libraries and their role within schools. Certainly, school libraries have been in decline and the use of evidence to show value is needed. As Ken Haycock noted in his 2003 report, The Crisis in Canada’s School Libraries: The Case for Reform and Reinvestment, “Across the country, teacher-librarians are losing their jobs or being reassigned. Collections are becoming depleted owing to budget cuts. Some principals believe that in the age of the Internet and the classroom workstation, the school library is an artifact” (9. Within this context, school librarians are looking to our research literature for evidence of the impact that school library programs have on learning outcomes and student success. They are integrating that evidence into their practice, and reflecting upon what can be improved locally. They are focusing on students and showing the impact of school libraries and

  2. Device for stretching tapes or cables intended for manipulators

    International Nuclear Information System (INIS)

    Baudoin, J.-C.; Oger, Robert.

    1975-01-01

    The invention relates to a device for stretching tapes (or cables) intended for remote handling devices. Said equipment consists of a spring system continuously applying a constant tensile stress to said tapes (or cables) in view of taking up the slack in the latter. Said spring system is fastened to a supporting bar able to be rigidly connected to a member of the remote handling device [fr

  3. Device for stretching tapes or cables intended for manipulators

    Energy Technology Data Exchange (ETDEWEB)

    Baudoin, J C; Oger, R

    1975-03-06

    The invention relates to a device for stretching tapes (or cables) intended for remote handling devices. Said equipment consists of a spring system continuously applying a constant tensile stress to said tapes (or cables) in view of taking up the slack in the latter. Said spring system is fastened to a supporting bar able to be rigidly connected to a member of the remote handling device.

  4. Stretched exponentials and power laws in granular avalanching

    Science.gov (United States)

    Head, D. A.; Rodgers, G. J.

    1999-02-01

    We introduce a model for granular surface flow which exhibits both stretched exponential and power law avalanching over its parameter range. Two modes of transport are incorporated, a rolling layer consisting of individual particles and the overdamped, sliding motion of particle clusters. The crossover in behaviour observed in experiments on piles of rice is attributed to a change in the dominant mode of transport. We predict that power law avalanching will be observed whenever surface flow is dominated by clustered motion.

  5. Fibril orientation redistribution induced by stretching of cellulose nanofibril hydrogels

    International Nuclear Information System (INIS)

    Josefsson, Gabriella; Gamstedt, E. Kristofer; Ahvenainen, Patrik; Mushi, Ngesa Ezekiel

    2015-01-01

    The mechanical performance of materials reinforced by cellulose nanofibrils is highly affected by the orientation of these fibrils. This paper investigates the nanofibril orientation distribution of films of partly oriented cellulose nanofibrils. Stripes of hydrogel films were subjected to different amount of strain and, after drying, examined with X-ray diffraction to obtain the orientation of the nanofibrils in the films, caused by the stretching. The cellulose nanofibrils had initially a random in-plane orientation in the hydrogel films and the strain was applied to the films before the nanofibrils bond tightly together, which occurs during drying. The stretching resulted in a reorientation of the nanofibrils in the films, with monotonically increasing orientation towards the load direction with increasing strain. Estimation of nanofibril reorientation by X-ray diffraction enables quantitative comparison of the stretch-induced orientation ability of different cellulose nanofibril systems. The reorientation of nanofibrils as a consequence of an applied strain is also predicted by a geometrical model of deformation of nanofibril hydrogels. Conversely, in high-strain cold-drawing of wet cellulose nanofibril materials, the enhanced orientation is promoted by slipping of the effectively stiff fibrils

  6. Tail modeling in a stretched magnetosphere 1. Methods and transformations

    International Nuclear Information System (INIS)

    Stern, D.P.

    1987-01-01

    A new method is developed for representing the magnetospheric field B as a distorted dipole field. Because delxB = 0 must be maintained,such a distortion may be viewed as a transformation of the vector potential A. The simplest form is a one-dimensional ''stretch transformation'' along the x axis, a generalization of a method introduced by Voigt. The transformation is concisely represented by the ''stretch function'' f(x), which is also a convenient tool for representing features of the substorm cycle. Onedimensional stretch transformations are extended to spherical, cylindrical, and parabolic coordinates and then to arbitrary coordinates. It is next shown that distortion transformations can be viewed as mappings of field lines from one pattern to another: Euler potentials are used in the derivation, but the final result only requires knowledge of the field and not of the potentials. General transformations in Cartesian and arbitrary coordinates are then derived,and applications to field modeling, field line motion, MHD modeling, and incompressible fluid dynamics are considered. copyrightAmerican Geophysical Union 1987

  7. Longitudinal Stretching for Maturation of Vascular Tissues Using Magnetic Forces

    Directory of Open Access Journals (Sweden)

    Timothy R. Olsen

    2016-11-01

    Full Text Available Cellular spheroids were studied to determine their use as “bioinks” in the biofabrication of tissue engineered constructs. Specifically, magnetic forces were used to mediate the cyclic longitudinal stretching of tissues composed of Janus magnetic cellular spheroids (JMCSs, as part of a post-processing method for enhancing the deposition and mechanical properties of an extracellular matrix (ECM. The purpose was to accelerate the conventional tissue maturation process via novel post-processing techniques that accelerate the functional, structural, and mechanical mimicking of native tissues. The results of a forty-day study of JMCSs indicated an expression of collagen I, collagen IV, elastin, and fibronectin, which are important vascular ECM proteins. Most notably, the subsequent exposure of fused tissue sheets composed of JMCSs to magnetic forces did not hinder the production of these key proteins. Quantitative results demonstrate that cyclic longitudinal stretching of the tissue sheets mediated by these magnetic forces increased the Young’s modulus and induced collagen fiber alignment over a seven day period, when compared to statically conditioned controls. Specifically, the elastin and collagen content of these dynamically-conditioned sheets were 35- and three-fold greater, respectively, at seven days compared to the statically-conditioned controls at three days. These findings indicate the potential of using magnetic forces in tissue maturation, specifically through the cyclic longitudinal stretching of tissues.

  8. Stretching Diagnostics and Mixing Properties In The Stratosphere

    Science.gov (United States)

    Legras, B.; Shuckburgh, E.

    The "finite size Lyapunov exponent" and the "effective diffusivity" are two diagnos- tics of mixing which have been recently introduced to investigate atmospheric flows. Both have been used to successfully identify the barriers to transport, for instance at the edge of the stratospheric polar vortex. Here we compare the two diagnostics in detail. The equivalent length has the advantage of arising as a mixing quantification from a rigid theoretical framework, however it has the disadvantage of being an aver- age quantity (the average around a tracer contour). The finite size Lyapunov exponent may be defined at any point in the flow, and quantifies the stretching properties expe- rienced by a fluid parcel both in its past and future evolution. In particular, the lines of maximum stretching at any time delineate the building blocks of the chaotic stirring. However the interpretation of the finite size Lyapunov exponent as a mixing time is less direct and depends on the alignment of tracer contours with the stretching lines.

  9. A Novel Stretch Sensor to Measure Venous Hemodynamics

    Directory of Open Access Journals (Sweden)

    Syrpailyne Wankhar

    2018-07-01

    Full Text Available Chronic venous insufficiency is a debilitating condition causing varicose veins and venous ulcers. The pathophysiology includes reflux and venous obstruction. The diagnosis is often made by clinical examination and confirmed by Venous Doppler studies. Plethysmography helps to quantitatively examine the reflux and diagnose the burden of deep venous pathology to better understand venous hemodynamics, which is not elicited by venous duplex examination alone. However, most of these tests are qualitative, expensive, and not easily available. In this paper, we demonstrate the potential use of a novel stretch sensor in the assessment of venous hemodynamics during different maneuvers by measuring the change in calf circumference. We designed the stretch sensor by using semiconductor strain gauges pasted onto a small metal bar to form a load cell. The elastic and Velcro material attached to the load cell form a belt. It converts the change in limb circumference to a proportional tension (force of distension when placed around the calf muscle. We recorded the change in limb circumference from arrays of stretch sensors by using an in-house data acquisition system. We calculated the venous volume (VV, venous filling index (VFI, ejection fraction (EF and residual venous volume (RVV on two normal subjects and on two patients to assess venous hemodynamics. The values (VV > 60 ml, VFI 60%, RVV 2ml/s, EF 35% in patients were comparable to those reported in the literature.

  10. Simulation of stretch forming with intermediate heat treatments of aircraft skins - A physically based modeling approach

    NARCIS (Netherlands)

    Kurukuri, S.; Miroux, Alexis; Wisselink, H.H.; van den Boogaard, Antonius H.

    2011-01-01

    In the aerospace industry stretch forming is often used to produce skin parts. During stretch forming a sheet is clamped at two sides and stretched over a die, such that the sheet gets the shape of the die. However for complex shapes it is necessary to use expensive intermediate heat-treatments in

  11. Granular compaction and stretched exponentials - Experiments and a numerical stochastic model

    Directory of Open Access Journals (Sweden)

    Nicolas Maxime

    2017-01-01

    Full Text Available We present a stochastic model to investigate the compaction kinetics of a granular material submitted to vibration. The model is compared to experimental results obtained with glass beads and with a cohesive powder. We also propose a physical interpretation of the characteristic time τ and the exponent β of the stretched exponential function widely used to represent the granular compaction kinetics, and we show that the characteristic time is proportional to the number of grains to move. The exponent β is expressed as a logarithmic compaction rate.

  12. DNA-cisplatin binding mechanism peculiarities studied with single molecule stretching experiments

    Science.gov (United States)

    Crisafuli, F. A. P.; Cesconetto, E. C.; Ramos, E. B.; Rocha, M. S.

    2012-02-01

    We propose a method to determine the DNA-cisplatin binding mechanism peculiarities by monitoring the mechanical properties of these complexes. To accomplish this task, we have performed single molecule stretching experiments by using optical tweezers, from which the persistence and contour lengths of the complexes can be promptly measured. The persistence length of the complexes as a function of the drug total concentration in the sample was used to deduce the binding data, from which we show that cisplatin binds cooperatively to the DNA molecule, a point which so far has not been stressed in binding equilibrium studies of this ligand.

  13. A discrete electromechanical model for human cardiac tissue: effects of stretch-activated currents and stretch conditions on restitution properties and spiral wave dynamics.

    Science.gov (United States)

    Weise, Louis D; Panfilov, Alexander V

    2013-01-01

    We introduce an electromechanical model for human cardiac tissue which couples a biophysical model of cardiac excitation (Tusscher, Noble, Noble, Panfilov, 2006) and tension development (adjusted Niederer, Hunter, Smith, 2006 model) with a discrete elastic mass-lattice model. The equations for the excitation processes are solved with a finite difference approach, and the equations of the mass-lattice model are solved using Verlet integration. This allows the coupled problem to be solved with high numerical resolution. Passive mechanical properties of the mass-lattice model are described by a generalized Hooke's law for finite deformations (Seth material). Active mechanical contraction is initiated by changes of the intracellular calcium concentration, which is a variable of the electrical model. Mechanical deformation feeds back on the electrophysiology via stretch-activated ion channels whose conductivity is controlled by the local stretch of the medium. We apply the model to study how stretch-activated currents affect the action potential shape, restitution properties, and dynamics of spiral waves, under constant stretch, and dynamic stretch caused by active mechanical contraction. We find that stretch conditions substantially affect these properties via stretch-activated currents. In constantly stretched medium, we observe a substantial decrease in conduction velocity, and an increase of action potential duration; whereas, with dynamic stretch, action potential duration is increased only slightly, and the conduction velocity restitution curve becomes biphasic. Moreover, in constantly stretched medium, we find an increase of the core size and period of a spiral wave, but no change in rotation dynamics; in contrast, in the dynamically stretching medium, we observe spiral drift. Our results may be important to understand how altered stretch conditions affect the heart's functioning.

  14. A discrete electromechanical model for human cardiac tissue: effects of stretch-activated currents and stretch conditions on restitution properties and spiral wave dynamics.

    Directory of Open Access Journals (Sweden)

    Louis D Weise

    Full Text Available We introduce an electromechanical model for human cardiac tissue which couples a biophysical model of cardiac excitation (Tusscher, Noble, Noble, Panfilov, 2006 and tension development (adjusted Niederer, Hunter, Smith, 2006 model with a discrete elastic mass-lattice model. The equations for the excitation processes are solved with a finite difference approach, and the equations of the mass-lattice model are solved using Verlet integration. This allows the coupled problem to be solved with high numerical resolution. Passive mechanical properties of the mass-lattice model are described by a generalized Hooke's law for finite deformations (Seth material. Active mechanical contraction is initiated by changes of the intracellular calcium concentration, which is a variable of the electrical model. Mechanical deformation feeds back on the electrophysiology via stretch-activated ion channels whose conductivity is controlled by the local stretch of the medium. We apply the model to study how stretch-activated currents affect the action potential shape, restitution properties, and dynamics of spiral waves, under constant stretch, and dynamic stretch caused by active mechanical contraction. We find that stretch conditions substantially affect these properties via stretch-activated currents. In constantly stretched medium, we observe a substantial decrease in conduction velocity, and an increase of action potential duration; whereas, with dynamic stretch, action potential duration is increased only slightly, and the conduction velocity restitution curve becomes biphasic. Moreover, in constantly stretched medium, we find an increase of the core size and period of a spiral wave, but no change in rotation dynamics; in contrast, in the dynamically stretching medium, we observe spiral drift. Our results may be important to understand how altered stretch conditions affect the heart's functioning.

  15. The effectiveness of combined prescription of ankle–foot orthosis and stretching program for the treatment of recalcitrant plantar fasciitis

    Directory of Open Access Journals (Sweden)

    Rehab A.E. Sallam

    2016-01-01

    Combined prescription of night-stretch ankle–foot orthosis and stretching exercises for plantar flexors and fascia had greater therapeutic effects compared with each treatment alone. Stretching exercises alone are not beneficial in the treatment of recalcitrant plantar fasciitis.

  16. Micropatterning stretched and aligned DNA for sequence-specific nanolithography

    Science.gov (United States)

    Petit, Cecilia Anna Paulette

    Techniques for fabricating nanostructured materials can be categorized as either "top-down" or "bottom-up". Top-down techniques use lithography and contact printing to create patterned surfaces and microfluidic channels that can corral and organize nanoscale structures, such as molecules and nanorods in contrast; bottom-up techniques use self-assembly or molecular recognition to direct the organization of materials. A central goal in nanotechnology is the integration of bottom-up and top-down assembly strategies for materials development, device design; and process integration. With this goal in mind, we have developed strategies that will allow this integration by using DNA as a template for nanofabrication; two top-down approaches allow the placement of these templates, while the bottom-up technique uses the specific sequence of bases to pattern materials along each strand of DNA. Our first top-down approach, termed combing of molecules in microchannels (COMMIC), produces microscopic patterns of stretched and aligned molecules of DNA on surfaces. This process consists of passing an air-water interface over end adsorbed molecules inside microfabricated channels. The geometry of the microchannel directs the placement of the DNA molecules, while the geometry of the airwater interface directs the local orientation and curvature of the molecules. We developed another top-down strategy for creating micropatterns of stretched and aligned DNA using surface chemistry. Because DNA stretching occurs on hydrophobic surfaces, this technique uses photolithography to pattern vinyl-terminated silanes on glass When these surface-, are immersed in DNA solution, molecules adhere preferentially to the silanized areas. This approach has also proven useful in patterning protein for cell adhesion studies. Finally, we describe the use of these stretched and aligned molecules of DNA as templates for the subsequent bottom-up construction of hetero-structures through hybridization

  17. Spasticity Measurement Based on Tonic Stretch Reflex Threshold in Children with Cerebral Palsy Using the PediAnklebot

    Directory of Open Access Journals (Sweden)

    Marco Germanotta

    2017-05-01

    Full Text Available Nowadays, objective measures are becoming prominent in spasticity assessment, to overcome limitations of clinical scales. Among others, Tonic Stretch Reflex Threshold (TSRT showed promising results. Previous studies demonstrated the validity and reliability of TSRT in spasticity assessment at elbow and ankle joints in adults. Purposes of the present study were to assess: (i the feasibility of measuring TSRT to evaluate spasticity at the ankle joint in children with Cerebral Palsy (CP, and (ii the correlation between objective measures and clinical scores. A mechatronic device, the pediAnklebot, was used to impose 50 passive stretches to the ankle of 10 children with CP and 3 healthy children, to elicit muscles response at 5 different velocities. Surface electromyography, angles, and angular velocities were recorded to compute dynamic stretch reflex threshold; TSRT was computed with a linear regression through angles and angular velocities. TSRTs for the most affected side of children with CP resulted into the biomechanical range (95.7 ± 12.9° and 86.7 ± 17.4° for Medial and Lateral Gastrocnemius, and 75.9 ± 12.5° for Tibialis Anterior. In three patients, the stretch reflex was not elicited in the less affected side. TSRTs were outside the biomechanical range in healthy children. However, no correlation was found between clinical scores and TSRT values. Here, we demonstrated the capability of TSRT to discriminate between spastic and non-spastic muscles, while no significant outcomes were found for the dorsiflexor muscle.

  18. Comparing the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men.

    Science.gov (United States)

    Ferguson, Steven L; Kim, Eonho; Seo, Dong-Il; Bemben, Michael G

    2013-12-01

    This study compared the effects of 3 weeks of upper-body vibration training, vibration and stretching, and stretching alone on shoulder flexibility in college-aged men. Twenty-one men were randomly assigned to vibration-stretching (VS; n = 8), vibration only (VO; n = 6), or stretching only (SO; n = 7) groups that trained 3 times per week for 3 weeks. All 3 groups performed 9 total sets of 30-second stretches. The VS group performed four 30-second upper-body vibration exercises and five 30-second upper-body stretching exercises. The VO group performed nine 30-second upper-body vibration exercises. The SO group performed nine 30-second upper-body stretching exercises. Shoulder flexion (SF), shoulder extension (SE), and shoulder transverse extension (STE) were assessed by a Leighton Flexometer and back scratch tests bilaterally (BSR, BSL) were measured via tape measure. A 1-way analysis of variance (ANOVA) evaluated groups at baseline and a 2-way repeated-measures ANOVA evaluated the interventions over time. At baseline, there were no group differences in age, height, or weight. There was a significant (p alone or combined with stretching, is a viable alternative to a standard stretching routine when attempting to increase shoulder flexibility. Adding vibration training to a flexibility regimen may improve the likelihood of regularly performing flexibility sessions because of increased variety.

  19. Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

    Science.gov (United States)

    Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

    2018-01-01

    We use Brownian dynamics simulations and analytical theory to compare two prominent types of single molecule transitions. One is the adsorption transition of a loop (a chain with two ends bound to an attractive substrate) driven by an attraction parameter ɛ and the other is the loop-stretch transition in a chain with one end attached to a repulsive substrate, driven by an external end-force F applied to the free end. Specifically, we compare the behavior of the respective order parameters of the transitions, i.e., the mean number of surface contacts in the case of the adsorption transition and the mean position of the chain end in the case of the loop-stretch transition. Close to the transition points, both the static behavior and the dynamic behavior of chains with different length N are very well described by a scaling ansatz with the scaling parameters (ɛ - ɛ*)Nϕ (adsorption transition) and (F - F*)Nν (loop-stretch transition), respectively, where ϕ is the crossover exponent of the adsorption transition and ν is the Flory exponent. We show that both the loop-stretch and the loop adsorption transitions provide an exceptional opportunity to construct explicit analytical expressions for the crossover functions which perfectly describe all simulation results on static properties in the finite-size scaling regime. Explicit crossover functions are based on the ansatz for the analytical form of the order parameter distributions at the respective transition points. In contrast to the close similarity in equilibrium static behavior, the dynamic relaxation at the two transitions shows qualitative differences, especially in the strongly ordered regimes. This is attributed to the fact that the surface contact dynamics in a strongly adsorbed chain is governed by local processes, whereas the end height relaxation of a strongly stretched chain involves the full spectrum of Rouse modes.

  20. Ca2+ influx and ATP release mediated by mechanical stretch in human lung fibroblasts

    International Nuclear Information System (INIS)

    Murata, Naohiko; Ito, Satoru; Furuya, Kishio; Takahara, Norihiro; Naruse, Keiji; Aso, Hiromichi; Kondo, Masashi; Sokabe, Masahiro; Hasegawa, Yoshinori

    2014-01-01

    Highlights: • Uniaxial stretching activates Ca 2+ signaling in human lung fibroblasts. • Stretch-induced intracellular Ca 2+ elevation is mainly via Ca 2+ influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca 2+ influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca 2+ concentration ([Ca 2+ ] i ) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca 2+ ] i transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca 2+ ] i . The stretch-induced [Ca 2+ ] i elevation was attenuated in Ca 2+ -free solution. In contrast, the increase of [Ca 2+ ] i by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd 3+ , ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca 2+ ] i elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca 2+ influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP

  1. Ca{sup 2+} influx and ATP release mediated by mechanical stretch in human lung fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Naohiko [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Ito, Satoru, E-mail: itori@med.nagoya-u.ac.jp [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Furuya, Kishio [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Takahara, Norihiro [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Naruse, Keiji [Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Okayama 700-8558 (Japan); Aso, Hiromichi; Kondo, Masashi [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Sokabe, Masahiro [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Hasegawa, Yoshinori [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan)

    2014-10-10

    Highlights: • Uniaxial stretching activates Ca{sup 2+} signaling in human lung fibroblasts. • Stretch-induced intracellular Ca{sup 2+} elevation is mainly via Ca{sup 2+} influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca{sup 2+} influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca{sup 2+} concentration ([Ca{sup 2+}]{sub i}) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca{sup 2+}]{sub i} transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca{sup 2+}]{sub i}. The stretch-induced [Ca{sup 2+}]{sub i} elevation was attenuated in Ca{sup 2+}-free solution. In contrast, the increase of [Ca{sup 2+}]{sub i} by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd{sup 3+}, ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca{sup 2+}]{sub i} elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca{sup 2+} influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP.

  2. Origin of stretched-exponential photoluminescence relaxation in size-separated silicon nanocrystals

    Directory of Open Access Journals (Sweden)

    Samuel L. Brown

    2017-05-01

    Full Text Available A detailed understanding of the photoluminescence (PL from silicon nanocrystals (SiNCs is convoluted by the complexity of the decay mechanism, including a stretched-exponential relaxation and the presence of both nanosecond and microsecond time scales. In this publication, we analyze the microsecond PL decay of size-resolved SiNC fractions in both full-spectrum (FS and spectrally resolved (SR configurations, where the stretching exponent and lifetime are used to deduce a probability distribution function (PDF of decay rates. For the PL decay measured at peak emission, we find a systematic shift and narrowing of the PDF in comparison to the FS measurements. In a similar fashion, we resolve the PL lifetime of the ‘blue’, ‘peak’, and ‘red’ regions of the spectrum and map PL decays of different photon energy onto their corresponding location in the PDF. A general trend is observed where higher and lower photon energies are correlated with shorter and longer lifetimes, respectively, which we relate to the PL line width and electron-phonon coupling.

  3. PEMBERIAN INFRA RED, STRIPPING DAN STRETCHING TERHADAP NYERI TENSION HEADACHE DI PUSKESMAS TAPUS

    Directory of Open Access Journals (Sweden)

    Cici Apriza Yanti

    2018-03-01

    Full Text Available Prevalence of headache in Indonesia is very high. More than 90% of patients consult a doctor. The aim of research is to know the difference of pain after giving Infra Red, Stripping, and Stretching to the pain of tension headache. This research design is quasi experiment with pre and post test design. Population in this research is all patient of tension headache at Tapus Health Center. Sampling using accidental sampling with 10 samples. The data were collected using observation sheet of pain caused by tension headache. Data analysis was done by computerized using Wilcoxon test. The results showed that the mean intensity of pain before the 5.60 decreased to 4.78 after intervention and the mean intensity of tenderness before the 6.10 decreased to 5.27 after the intervention. The results of analysis showed that there was a difference in the intensity of pain (p = 0,005 and tenderness (p = 0,005.It can be concluded that therapy with Infra Red (IR, Stripping, and Stretching is effective to decreased pain intensity due to tension headache. For that it is expected to patients with pain complaints to tension headache to be always active and disciplined follow effective therapy in reducing the intensity of pain. Prevalensi sakit kepala di Indonesia sangatlah tinggi. Lebih dari 90% pasien yang berkonsultasi ke dokter. Penelitian ini bertujuan untuk mengetahui perbedaan nyeri tekan dan gerak setelah pemberian Infra Red, Stripping, dan Stretching terhadap nyeri pada kasus tension headache di Puskesmas Tapus Kabupaten Pasaman tahun 2016. Desain penelitian ini adalah quasi eksperiment dengan desain pre dan post test. Populasi pada penelitian adalah seluruh pasien tension headache di Puskesmas Tapus pada bulan Juni sampai Juli tahun 2016. Pengambilan sampel menggunakan teknik accidental sampling sehingga didapatkan sampel sebanyak 10 orang. Pengumpulan data penelitian menggunakan lembar observasi intensitas nyeri akibat tension headache. Analisis data

  4. Passive Stretch Induces Structural and Functional Maturation of Engineered Heart Muscle as Predicted by Computational Modeling.

    Science.gov (United States)

    Abilez, Oscar J; Tzatzalos, Evangeline; Yang, Huaxiao; Zhao, Ming-Tao; Jung, Gwanghyun; Zöllner, Alexander M; Tiburcy, Malte; Riegler, Johannes; Matsa, Elena; Shukla, Praveen; Zhuge, Yan; Chour, Tony; Chen, Vincent C; Burridge, Paul W; Karakikes, Ioannis; Kuhl, Ellen; Bernstein, Daniel; Couture, Larry A; Gold, Joseph D; Zimmermann, Wolfram H; Wu, Joseph C

    2018-02-01

    The ability to differentiate human pluripotent stem cells (hPSCs) into cardiomyocytes (CMs) makes them an attractive source for repairing injured myocardium, disease modeling, and drug testing. Although current differentiation protocols yield hPSC-CMs to >90% efficiency, hPSC-CMs exhibit immature characteristics. With the goal of overcoming this limitation, we tested the effects of varying passive stretch on engineered heart muscle (EHM) structural and functional maturation, guided by computational modeling. Human embryonic stem cells (hESCs, H7 line) or human induced pluripotent stem cells (IMR-90 line) were differentiated to hPSC-derived cardiomyocytes (hPSC-CMs) in vitro using a small molecule based protocol. hPSC-CMs were characterized by troponin + flow cytometry as well as electrophysiological measurements. Afterwards, 1.2 × 10 6 hPSC-CMs were mixed with 0.4 × 10 6 human fibroblasts (IMR-90 line) (3:1 ratio) and type-I collagen. The blend was cast into custom-made 12-mm long polydimethylsiloxane reservoirs to vary nominal passive stretch of EHMs to 5, 7, or 9 mm. EHM characteristics were monitored for up to 50 days, with EHMs having a passive stretch of 7 mm giving the most consistent formation. Based on our initial macroscopic observations of EHM formation, we created a computational model that predicts the stress distribution throughout EHMs, which is a function of cellular composition, cellular ratio, and geometry. Based on this predictive modeling, we show cell alignment by immunohistochemistry and coordinated calcium waves by calcium imaging. Furthermore, coordinated calcium waves and mechanical contractions were apparent throughout entire EHMs. The stiffness and active forces of hPSC-derived EHMs are comparable with rat neonatal cardiomyocyte-derived EHMs. Three-dimensional EHMs display increased expression of mature cardiomyocyte genes including sarcomeric protein troponin-T, calcium and potassium ion channels, β-adrenergic receptors, and t

  5. Modeling steady-state dynamics of macromolecules in exponential-stretching flow using multiscale molecular-dynamics-multiparticle-collision simulations.

    Science.gov (United States)

    Ghatage, Dhairyasheel; Chatterji, Apratim

    2013-10-01

    We introduce a method to obtain steady-state uniaxial exponential-stretching flow of a fluid (akin to extensional flow) in the incompressible limit, which enables us to study the response of suspended macromolecules to the flow by computer simulations. The flow field in this flow is defined by v(x) = εx, where v(x) is the velocity of the fluid and ε is the stretch flow gradient. To eliminate the effect of confining boundaries, we produce the flow in a channel of uniform square cross section with periodic boundary conditions in directions perpendicular to the flow, but simultaneously maintain uniform density of fluid along the length of the tube. In experiments a perfect elongational flow is obtained only along the axis of symmetry in a four-roll geometry or a filament-stretching rheometer. We can reproduce flow conditions very similar to extensional flow near the axis of symmetry by exponential-stretching flow; we do this by adding the right amounts of fluid along the length of the flow in our simulations. The fluid particles added along the length of the tube are the same fluid particles which exit the channel due to the flow; thus mass conservation is maintained in our model by default. We also suggest a scheme for possible realization of exponential-stretching flow in experiments. To establish our method as a useful tool to study various soft matter systems in extensional flow, we embed (i) spherical colloids with excluded volume interactions (modeled by the Weeks-Chandler potential) as well as (ii) a bead-spring model of star polymers in the fluid to study their responses to the exponential-stretched flow and show that the responses of macromolecules in the two flows are very similar. We demonstrate that the variation of number density of the suspended colloids along the direction of flow is in tune with our expectations. We also conclude from our study of the deformation of star polymers with different numbers of arms f that the critical flow gradient ε

  6. Mechanical stretching for tissue engineering: two-dimensional and three-dimensional constructs.

    Science.gov (United States)

    Riehl, Brandon D; Park, Jae-Hong; Kwon, Il Keun; Lim, Jung Yul

    2012-08-01

    Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols.

  7. Mechanical stretching effect on the actuator performance of cellulose electroactive paper

    International Nuclear Information System (INIS)

    Kim, Jung-Hwan; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

    2009-01-01

    The mechanical stretching effect on the actuating performance of electroactive cellulose paper (EAPap) was studied. A lattice elongation of cellulose fibrils due to in-plane tensile stress along the stretching direction was observed by the x-ray diffraction method. The shrinkage of the fibril diameter as a function of stretching ratio was confirmed by surface and cross-sectional images. While the actuator performance in terms of bending displacement decreased as the stretching ratio increased, the resonance frequency linearly increased as the stretching ratio increased, which was compared with the theoretical frequency data found from a cantilever beam model. The actuator efficiency was evaluated from the electrical input power consumption and the mechanical output power of an EAPap actuator. It was revealed that the stretching process increased the electro-mechanical efficiency of the EAPap actuator. The mechanism of the influence of the stretching effect on the performance of an EAPap actuator is discussed

  8. Biaxial Stretch Improves Elastic Fiber Maturation, Collagen Arrangement, and Mechanical Properties in Engineered Arteries.

    Science.gov (United States)

    Huang, Angela H; Balestrini, Jenna L; Udelsman, Brooks V; Zhou, Kevin C; Zhao, Liping; Ferruzzi, Jacopo; Starcher, Barry C; Levene, Michael J; Humphrey, Jay D; Niklason, Laura E

    2016-06-01

    Tissue-engineered blood vessels (TEVs) are typically produced using the pulsatile, uniaxial circumferential stretch to mechanically condition and strengthen the arterial grafts. Despite improvements in the mechanical integrity of TEVs after uniaxial conditioning, these tissues fail to achieve critical properties of native arteries such as matrix content, collagen fiber orientation, and mechanical strength. As a result, uniaxially loaded TEVs can result in mechanical failure, thrombus, or stenosis on implantation. In planar tissue equivalents such as artificial skin, biaxial loading has been shown to improve matrix production and mechanical properties. To date however, multiaxial loading has not been examined as a means to improve mechanical and biochemical properties of TEVs during culture. Therefore, we developed a novel bioreactor that utilizes both circumferential and axial stretch that more closely simulates loading conditions in native arteries, and we examined the suture strength, matrix production, fiber orientation, and cell proliferation. After 3 months of biaxial loading, TEVs developed a formation of mature elastic fibers that consisted of elastin cores and microfibril sheaths. Furthermore, the distinctive features of collagen undulation and crimp in the biaxial TEVs were absent in both uniaxial and static TEVs. Relative to the uniaxially loaded TEVs, tissues that underwent biaxial loading remodeled and realigned collagen fibers toward a more physiologic, native-like organization. The biaxial TEVs also showed increased mechanical strength (suture retention load of 303 ± 14.53 g, with a wall thickness of 0.76 ± 0.028 mm) and increased compliance. The increase in compliance was due to combinatorial effects of mature elastic fibers, undulated collagen fibers, and collagen matrix orientation. In conclusion, biaxial stretching is a potential means to regenerate TEVs with improved matrix production, collagen organization, and mechanical

  9. A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery.

    Science.gov (United States)

    Tracy, Paige V; DeLancey, John O; Ashton-Miller, James A

    2016-02-01

    Because levator ani (LA) muscle injuries occur in approximately 13% of all vaginal births, insights are needed to better prevent them. In Part I of this paper, we conducted an analysis of the bony and soft tissue factors contributing to the geometric "capacity" of the maternal pelvis and pelvic floor to deliver a fetal head without incurring stretch injury of the maternal soft tissue. In Part II, we quantified the range in demand, represented by the variation in fetal head size and shape, placed on the maternal pelvic floor. In Part III, we analyzed the capacity-to-demand geometric ratio, g, in order to determine whether a mother can deliver a head of given size without stretch injury. The results of a Part I sensitivity analysis showed that initial soft tissue loop length (SL) had the greatest effect on maternal capacity, followed by the length of the soft tissue loop above the inferior pubic rami at ultimate crowning, then subpubic arch angle (SPAA) and head size, and finally the levator origin separation distance. We found the more caudal origin of the puborectal portion of the levator muscle helps to protect it from the stretch injuries commonly observed in the pubovisceral portion. Part II fetal head molding index (MI) and fetal head size revealed fetal head circumference values ranging from 253 to 351 mm, which would increase up to 11 mm upon face presentation. The Part III capacity-demand analysis of g revealed that, based on geometry alone, the 10th percentile maternal capacity predicted injury for all head sizes, the 25th percentile maternal capacity could deliver half of all head sizes, while the 50th percentile maternal capacity could deliver a head of any size without injury. If ultrasound imaging could be operationalized to make measurements of ratio g, it might be used to usefully inform women on their level of risk for levator injury during vaginal birth.

  10. Nucleolar targeting of proteins by the tandem array of basic amino acid stretches identified in the RNA polymerase I-associated factor PAF49

    International Nuclear Information System (INIS)

    Ushijima, Ryujiro; Matsuyama, Toshifumi; Nagata, Izumi; Yamamoto, Kazuo

    2008-01-01

    There is accumulating evidence to indicate that the regulation of subnuclear compartmentalization plays important roles in cellular processes. The RNA polymerase I-associated factor PAF49 has been shown to accumulate in the nucleolus in growing cells, but disperse into the nucleoplasm in growth-arrested cells. Serial deletion analysis revealed that amino acids 199-338 were necessary for the nucleolar localization of PAF49. Combinatorial point mutation analysis indicated that the individual basic amino acid stretches (BS) within the central (BS1-4) and the C-terminal (BS5 and 6) regions may cooperatively confer the nucleolar localization of PAF49. Addition of the basic stretches in tandem to a heterologous protein, such as the interferon regulatory factor-3, translocated the tagged protein into the nucleolus, even in the presence of an intrinsic nuclear export sequence. Thus, tandem array of the basic amino acid stretches identified here functions as a dominant nucleolar targeting sequence

  11. Stretched graphene tented by polycaprolactone and polypyrrole net–bracket for neurotransmitter detection

    International Nuclear Information System (INIS)

    Wang, Zhenzhen; Ying, Ye; Li, Li; Xu, Ting; Wu, Yiping; Guo, Xiaoyu; Wang, Feng; Shen, Haojie; Wen, Ying; Yang, Haifeng

    2017-01-01

    Highlights: • A new DA sensor is constructed with RGO and electrospun polymer fiber film. • RGO sheets can be mechanically stretched by the as-fabricated net-brackets. • The DA sensor shows highly catalytic activity toward the oxidation of dopamine. • The as-prepared sensor is used to detect DA in injection or urine. • The protocol to make sensors in large scale way has good reproducibility. - Abstract: A net-bracket built out from the core@shell structure of chemically oxidized polypyrrole (PPy) coated electrospun polycaprolactone (PCL) nanofibers, and the following surface modification of a thin layer of positively charged poly(dimethyl diallyl ammonium chloride) (PDDA) has been applied for stretching the reduced graphene oxide (RGO) sheets to some extent with the electrochemical deposition method. The as-formed RGO/PDDA/PCL@PPy nanocomposites were investigated by using scanning electron microscopy, transmission electron microscope, X-ray diffraction and Raman spectroscopy. The graphene tented by the net-bracket showed remarkable electrocatalytic properties in detecting the neurotransmitter dopamine (DA). Low detection limit of 0.34 μM (S/N = 3) with the wide linear detection range from 4 μM to 690 μM was obtained. The successful determination of DA in real urine samples and DA injection were achieved. Such attractive fabrication strategy can be extended to make other graphene sheet-based sensors.

  12. Stretched graphene tented by polycaprolactone and polypyrrole net–bracket for neurotransmitter detection

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhenzhen; Ying, Ye; Li, Li; Xu, Ting; Wu, Yiping; Guo, Xiaoyu; Wang, Feng; Shen, Haojie; Wen, Ying, E-mail: ying.wen@shnu.edu.cn; Yang, Haifeng, E-mail: Hfyang@shnu.edu.cn

    2017-02-28

    Highlights: • A new DA sensor is constructed with RGO and electrospun polymer fiber film. • RGO sheets can be mechanically stretched by the as-fabricated net-brackets. • The DA sensor shows highly catalytic activity toward the oxidation of dopamine. • The as-prepared sensor is used to detect DA in injection or urine. • The protocol to make sensors in large scale way has good reproducibility. - Abstract: A net-bracket built out from the core@shell structure of chemically oxidized polypyrrole (PPy) coated electrospun polycaprolactone (PCL) nanofibers, and the following surface modification of a thin layer of positively charged poly(dimethyl diallyl ammonium chloride) (PDDA) has been applied for stretching the reduced graphene oxide (RGO) sheets to some extent with the electrochemical deposition method. The as-formed RGO/PDDA/PCL@PPy nanocomposites were investigated by using scanning electron microscopy, transmission electron microscope, X-ray diffraction and Raman spectroscopy. The graphene tented by the net-bracket showed remarkable electrocatalytic properties in detecting the neurotransmitter dopamine (DA). Low detection limit of 0.34 μM (S/N = 3) with the wide linear detection range from 4 μM to 690 μM was obtained. The successful determination of DA in real urine samples and DA injection were achieved. Such attractive fabrication strategy can be extended to make other graphene sheet-based sensors.

  13. Computation of nuclear reactor parameters using a stretch Kalman filtering

    International Nuclear Information System (INIS)

    Zwingelstein, G.; Poujol, A.

    1976-01-01

    A method of nonlinear stochastic filtering, the stretched Karman filter, is used for the estimation of two basic parameters involved in the control of nuclear reactor start-up. The corresponding algorithm is stored in a small Multi-8 computer and tested with data recorded for the Ulysse reactor (I.N.S.T.N.). The various practical problems involved in using the algorithm are examined: filtering initialization, influence of the model... The quality and time saving obtained in the computation make it possible for a real time operation, the computer being connected with the reactor [fr

  14. Muscle damage induced by stretch-shortening cycle exercise.

    Science.gov (United States)

    Kyröläinen, H; Takala, T E; Komi, P V

    1998-03-01

    Strenuous stretch-shortening cycle exercise was used as a model to study the leakage of proteins from skeletal muscle. The analysis included serum levels of creatine kinase (S-CK), myoglobin (S-Mb), and carbonic anhydrase (S-CA III). Blood samples from power- (N=11) and endurance-trained (N=10) athletes were collected before, 0, and 2 h after the exercise, which consisted of a total of 400 jumps. The levels of all determined myocellular proteins increased immediately after the exercise (P exercise, and the ratio of S-CA III and S-Mb decreased (P recruitment order of motor units, and/or differences in training background.

  15. Identification of the Process of Dynamic Stretching of Threads in Warp Knitting Technology Part II: Experimental Identification of the Process of Stretching Threads, with Verification of Rheological Models

    Directory of Open Access Journals (Sweden)

    Prążyńska Aleksandra

    2018-03-01

    Full Text Available The study is a continuation of the first part of the publication, concerning the theoretical analysis of sensitivity of rheological models of dynamically stretched thread. This part presents the experimental research on the characteristics of stretching forces as a function of time, in the context of comparing the obtained results with theoretical data.

  16. Impact of the configuration of stretching and ocean-atmosphere coupling on tropical cyclone activity in the variable-resolution GCM ARPEGE

    Energy Technology Data Exchange (ETDEWEB)

    Daloz, Anne Sophie; Chauvin, Fabrice [CNRM-GAME, Groupe de Modelisation Grande Echelle et Climat, Toulouse Cedex 1 (France); Roux, Frank [Universite de Toulouse, Laboratoire d' Aerologie, Centre National de la Recherche Scientifique, Toulouse (France)

    2012-11-15

    This study starts by investigating the impact of the configuration of the variable-resolution atmospheric grid on tropical cyclone (TC) activity. The French atmospheric general circulation model ARPEGE, the grid of which is rotated and stretched over the North Atlantic basin, was used with prescribed sea surface temperatures. The study clearly shows that changing the position of the stretching pole strongly modifies the representation of TC activity over the North Atlantic basin. A pole in the centre of the North Atlantic basin provides the best representation of the TC activity for this region. In a second part, the variable-resolution climate model ARPEGE is coupled with the European oceanic global climate model NEMO in order to study the impact of ocean-atmosphere coupling on TC activity over the North Atlantic basin. Two pre-industrial runs, a coupled simulation and a simulation forced by the sea surface temperatures from the coupled one, are compared. The results show that the coupled simulation is more active in the Caribbean Sea and the Gulf of Mexico while the forced simulation is more active over eastern Florida and the eastern Atlantic. The difference in the distribution of TC activity is certainly linked with the location of TC genesis. In the forced simulation, tropical cyclogenesis is closer to the west African coast than in the coupled simulation. Moreover, the difference in TC activity over the eastern Atlantic seems to be related to two different mechanisms: the difference in African easterly wave activity over the west of Africa and the cooling produced, in the coupled simulation, by African easterly waves over the eastern Atlantic. Finally, the last part studies the impact of changing the frequency of ocean-atmosphere coupling on Atlantic TC activity. Increasing the frequency of coupling decreases the density of TC activity over the North Atlantic basin. However, it does not modify the spatial distribution of the TC activity. TC rainfalls are

  17. Effects of Stretching by P.N.F and Harmonic Techniques on Hamstring Flexibility

    Directory of Open Access Journals (Sweden)

    Hassan Shakeri

    2006-01-01

    Full Text Available Objective: Improving of muscle flexibility is an important issue in physiotherapy and sport sciences. There are many methods for increasing muscle length and decreasing muscle stiffness. In research findings, PNF method has been found to be better than static and ballistic methods. There is another method named Harmonic technique (introduced by E. Lederman 1997 that has been claimed to be more effective, but there is not enough documentation about this claim. Aim of this study was to compare effects of stretching by PNF and harmonic techniques on hamstring flexibility. Materials & Methods: This research is a RCT study in that 45 colledge students aged 18-35 years were arranged in three groups (Harmonic, P.N.F, and control. Subjects haven’t had any painful pathology in low-back and lower extremities for last six months. Subjects had limited hamstring length (20 degrees deficiency in Active-Knee-Extension test and hadn’t professional sport activities. Dependent variablies were muscle stiffness and hamstring length which popliteal angle in AKE test was its indirect index. In pilot study, reliability of measurement of these variables were approved. Then hamstring muscle of subjects in harmonic and PNF groups were stretched by harmonic and PNF methods for six weeks, 5 minute per day and 3d/wks, whereas control group hadn’t any exercise. Results: Findings of this study showed that in both used techniques, changes of hamstring length were significant (P=0.000, but in control group there wasn’t significant change. There wasn’t significant differences between changes of hamstring length in PNF and Harmonic groups. Only in harmonic group, muscle stiffness had significant changes (P<0.03. Conclusion: According to findings of this research, both harmonic and PNF methods equally increased length of hamstring, and harmonic technique can be used as an alternative stretching method for other techniques. Maybe harmonic technique is better than PNF

  18. Stretch independent regulation of prostaglandin E(2) production within the isolated guinea-pig lamina propria.

    Science.gov (United States)

    Nile, Christopher J; de Vente, Jan; Gillespie, James I

    2010-02-01

    To use an isolated preparation of the guinea-pig bladder lamina propria (LP) to investigate the effects of adenosine tri-phosphate (ATP) and nitric oxide (NO) on the release of prostaglandin E(2) (PGE(2)). The bladders of female guinea-pigs (200-400 g) were isolated and opened to expose the urothelial surface. The LP was dissected free of the underlying detrusor muscle and cut into strips from the dome to base. Strips were then incubated in Krebs buffer at 37 degrees C. Each tissue piece was then exposed to the stable ATP analogue, BzATP, and a NO donor, diethylamine-NONOate (DEANO), and the effect on PGE(2) output into the supernatant determined using the Parameter(TM) PGE(2) enzyme immunoassay kit (R & D Systems, Abingdon, UK). Experiments were repeated in the presence of purinergic receptor and cyclooxygenase (COX) enzymes, COX I and COX II, antagonists. The cellular location of COX I, COX II and neuronal NO synthase (nNOS) within the bladder LP was also determined by immunohistochemistry. PGE(2) production was significantly increased by BzATP. Antagonist studies showed the purinergic stimulation involved both P(2)X and P(2)Y receptors. The BzATP response was inhibited by the COX inhibitor indomethacin (COX I >COX II) but not by DUP 697 (COX II >COX I). Thus, BzATP stimulation occurs because of COX I stimulation. NO had no effect on PGE(2) production over the initial 10 min of an exposure. However, PGE(2) output was increased 100 min after exposure to the NO donor. In the presence of NO, the BzATP stimulation was abolished. Immunohistochemistry was used to confirm the location of COX I to the basal and inner intermediate urothelial layers and to cells within the diffuse layer of LP interstitial cells. In addition, nNOS was also located in the basal urothelial layers whilst COX II was found in the interstitial cell layers. There is complex interaction between ATP and NO to modulate PGE(2) release from the bladder LP in the un-stretched preparation. Such

  19. Heat and mass transfer of a second grade magnetohydrodynamic fluid over a convectively heated stretching sheet

    Directory of Open Access Journals (Sweden)

    Kalidas Das

    2016-10-01

    Full Text Available The present work is concerned with heat and mass transfer of an electrically conducting second grade MHD fluid past a semi-infinite stretching sheet with convective surface heat flux. The analysis accounts for thermophoresis and thermal radiation. A similarity transformations is used to reduce the governing equations into a dimensionless form. The local similarity equations are derived and solved using Nachtsheim-Swigert shooting iteration technique together with Runge–Kutta sixth order integration scheme. Results for various flow characteristics are presented through graphs and tables delineating the effect of various parameters characterizing the flow. Our analysis explores that the rate of heat transfer enhances with increasing the values of the surface convection parameter. Also the fluid velocity and temperature in the boundary layer region rise significantly for increasing the values of thermal radiation parameter.

  20. Labrets: Piercing and Stretching on the Northwest Coast and in Amazonia

    Directory of Open Access Journals (Sweden)

    Jenny Reddish

    2014-05-01

    Full Text Available This article examines the practice of piercing and stretching the lip in order to accommodate a labret in two regions: the North American Northwest Coast (with historical examples from Tlingit and Haida groups and lowland South America (utilizing ethnographic writings on Suya and Kayapo communities. Drawing on the recent ‘sensorial turn’ within anthropology, I suggest an approach which goes beyond considerations of the symbolism of body ornaments and analyses how the infliction of pain they involve can be manipulated to serve social ends at a local level. Also discussed is the use of labrets within global ‘mediascapes’ (Appadurai 1996 by Kayapo and Northwest Coast groups in the context of self-representation and the politicization of ‘culture’ (Wright 1998.

  1. Tangential stretching rate (TSR) analysis of non premixed reactive flows

    KAUST Repository

    Valorani, Mauro

    2016-10-16

    We discuss how the Tangential stretching rate (TSR) analysis, originally developed and tested for spatially homogeneous systems (batch reactors), is extended to spatially non homogeneous systems. To illustrate the effectiveness of the TSR diagnostics, we study the ignition transient in a non premixed, reaction–diffusion model in the mixture fraction space, whose dependent variables are temperature and mixture composition. The reactive mixture considered is syngas/air. A detailed H2/CO mechanism with 12 species and 33 chemical reactions is employed. We will discuss two cases, one involving only kinetics as a model of front propagation purely driven by spontaneous ignition, the other as a model of deflagration wave involving kinetics/diffusion coupling. We explore different aspects of the system dynamics such as the relative role of diffusion and kinetics, the evolution of kinetic eigenvalues, and of the tangential stretching rates computed by accounting for the combined action of diffusion and kinetics as well for kinetics only. We propose criteria based on the TSR concept which allow to identify the most ignitable conditions and to discriminate between spontaneous ignition and deflagration front.

  2. Analysis of a Stretched Derivative Aircraft with Open Rotor Propulsion

    Science.gov (United States)

    Berton, Jeffrey J.; Hendricks, Eric S.; Haller, William J.; Guynn, Mark D.

    2015-01-01

    Research into advanced, high-speed civil turboprops received significant attention during the 1970s and 1980s when fuel efficiency was the driving focus of U.S. aeronautical research. But when fuel prices declined sharply there was no longer sufficient motivation to continue maturing the technology. Recent volatility in fuel prices and increasing concern for aviation's environmental impact, however, have renewed interest in unducted, open rotor propulsion and revived research by NASA and a number of engine manufacturers. Recently, NASA and General Electric have teamed to conduct several investigations into the performance and noise of an advanced, single-aisle transport with open rotor propulsion. The results of these initial studies indicate open rotor engines have the potential to provide significant reduction in fuel consumption compared to aircraft using turbofan engines with equivalent core technology. In addition, noise analysis of the concept indicates that an open rotor aircraft in the single-aisle transport class would be able to meet current noise regulations with margin. The behavior of derivative open rotor transports is of interest. Heavier, "stretched" derivative aircraft tend to be noisier than their lighter relatives. Of particular importance to the business case for the concept is how the noise margin changes relative to regulatory limits within a family of similar open rotor aircraft. The subject of this report is a performance and noise assessment of a notional, heavier, stretched derivative airplane equipped with throttle-push variants of NASA's initial open rotor engine design.

  3. Harmonics analysis of the photonic time stretch system.

    Science.gov (United States)

    Mei, Yuan; Xu, Boyu; Chi, Hao; Jin, Tao; Zheng, Shilie; Jin, Xiaofeng; Zhang, Xianmin

    2016-09-10

    Photonic time stretch (PTS) has been intensively investigated in recent decades due to its potential application to ultra-wideband analog-to-digital conversion. A high-speed analog signal can be captured by an electronic analog-to-digital converter (ADC) with the help of the PTS technique, which slows down the speed of signal in the photonic domain. Unfortunately, the process of the time stretch is not linear due to the nonlinear modulation of the electro-optic intensity modulator in the PTS system, which means the undesired harmonics distortion. In this paper, we present an exact analytical model to fully characterize the harmonics generation in the PTS systems for the first time, to the best of our knowledge. We obtain concise and closed-form expressions for all harmonics of the PTS system with either a single-arm Mach-Zehnder modulator (MZM) or a push-pull MZM. The presented model can largely simplify the PTS system design and the system parameters estimation, such as system bandwidth, harmonics power, time-bandwidth product, and dynamic range. The correctness of the mathematic model is verified by the numerical and experimental results.

  4. Static stretching does not alter pre and post-landing muscle activation

    Directory of Open Access Journals (Sweden)

    Moss Wesley R

    2011-05-01

    Full Text Available Abstract Background Static stretching may result in various strength and power deficiencies. Prior research has not determined, however, if static stretching causes a change in muscle activation during a functional task requiring dynamic stability. The purpose of this study was to determine if static stretching has an effect on mean pre and postlanding muscle (vastus medialis VM, vastus lateralis VL, medial hamstring MH, and biceps femoris BF activity. Methods 26 healthy, physically active subjects were recruited, from which 13 completed a 14-day static stretching regimen for the quadriceps and hamstrings. Using the data from the force plate and EMG readings, a mean of EMG amplitude was calculated for 150 msec before and after landing. Each trial was normalized to an isometric reference position. Means were calculated for the VM, VL, MH, and BF from 5 trials in each session. Measures were collected pre, immediately following the 1st stretching session, and following 2 weeks of stretching. Results A 14-day static stretching regimen resulted in no significant differences in pre or postlanding mean EMG amplitude during a drop landing either acutely or over a 14-day period. Conclusions Static stretching, done acutely or over a 14-day period does not result in measurable differences of mean EMG amplitude during a drop landing. Static stretching may not impede dynamic stability of joints about which stretched muscles cross.

  5. The long string at the stretched horizon and the entropy of large non-extremal black holes

    International Nuclear Information System (INIS)

    Mertens, Thomas G.; Verschelde, Henri; Zakharov, Valentin I.

    2016-01-01

    We discuss how long strings can arise at the stretched horizon and how they can account for the Bekenstein-Hawking entropy. We use the thermal scalar field theory to derive the asymptotic density of states and corresponding stress tensor of a microcanonical long string gas in Rindler space. We show that the equality of the Hagedorn and Hawking temperatures gives rise to the tree-level entropy of large black holes in accordance with the Bekenstein-Hawking-Wald formula.

  6. The long string at the stretched horizon and the entropy of large non-extremal black holes

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, Thomas G. [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States); Ghent University, Department of Physics and Astronomy,Krijgslaan, 281-S9, 9000 Gent (Belgium); Verschelde, Henri [Ghent University, Department of Physics and Astronomy,Krijgslaan, 281-S9, 9000 Gent (Belgium); Zakharov, Valentin I. [ITEP,B. Cheremushkinskaya 25, Moscow 117218 (Russian Federation); Moscow Institute Phys. & Technol.,Dolgoprudny, Moscow Region 141700 (Russian Federation); School of Biomedicine, Far Eastern Federal University,Sukhanova str 8, Vladivostok 690950 (Russian Federation)

    2016-02-04

    We discuss how long strings can arise at the stretched horizon and how they can account for the Bekenstein-Hawking entropy. We use the thermal scalar field theory to derive the asymptotic density of states and corresponding stress tensor of a microcanonical long string gas in Rindler space. We show that the equality of the Hagedorn and Hawking temperatures gives rise to the tree-level entropy of large black holes in accordance with the Bekenstein-Hawking-Wald formula.

  7. Regulation of inward rectifier potassium current ionic channel remodeling by AT1 -Calcineurin-NFAT signaling pathway in stretch-induced hypertrophic atrial myocytes.

    Science.gov (United States)

    He, Jionghong; Xu, Yanan; Yang, Long; Xia, Guiling; Deng, Na; Yang, Yongyao; Tian, Ye; Fu, Zenan; Huang, Yongqi

    2018-05-02

    Previous studies have shown that the activation of angiotensin II receptor type I (AT 1 ) is attributed to cardiac remodeling stimulated by increased heart load, and that it is followed by the activation of the calcineurin-nuclear factor of activated T-cells (NFAT) signaling pathway. Additionally, AT 1 has been found to be a regulator of cardiocyte ionic channel remodeling, and calcineurin-NFAT signals participate in the regulation of cardiocyte ionic channel expression. A hypothesis therefore follows that stretch stimulation may regulate cardiocyte ionic channel remodeling by activating the AT 1 -calcineurin-NFAT pathway. Here, we investigated the role of the AT 1 -calcineurin-NFAT pathway in the remodeling of inward rectifier potassium (I k1 ) channel, in addition to its role in changing action potential, in stretch-induced hypertrophic atrial myocytes of neonatal rats. Our results showed that increased stretch significantly led to atrial myocytes hypertrophy; it also increased the activity of calcineurin enzymatic activity, which was subsequently attenuated by telmisartan or cyclosporine-A. The level of NFAT 3 protein in nuclear extracts, the mRNA and protein expression of Kir2.1 in whole cell extracts, and the density of I k1 were noticeably increased in stretched samples. Stretch stimulation significantly shortened the action potential duration (APD) of repolarization at the 50% and 90% level. Telmisartan, cyclosporine-A, and 11R-VIVIT attenuated stretch-induced alterations in the levels of NFAT 3 , mRNA and protein expression of Kir2.1, the density of I k1 , and the APD. Our findings suggest that the AT 1 -calcineurin-NFAT signaling pathway played an important role in regulating I k1 channel remodeling and APD change in stretch-induced hypertrophic atrial myocytes of neonatal rats. This article is protected by copyright. All rights reserved.

  8. Design and experimental investigation of a stretched parabolic linear Fresnel reflector collecting system

    International Nuclear Information System (INIS)

    Zhu, Yanqing; Shi, Jifu; Li, Yujian; Wang, Leilei; Huang, Qizhang; Xu, Gang

    2016-01-01

    Highlights: • A parabolic primary mirror field is designed to reduce the gap between adjacent mirrors. • The movable receiver can reduce the end losses. • The thermal efficiency of 66% is achieved at Guangzhou in winter. - Abstract: This paper proposes a stretched parabolic linear Fresnel reflector (SPLFR) collecting system. The primary optical mirror field of the SPLFR collecting system and the second-stage concentrator of compound parabolic collector are designed. The mirrors located at the parabolic line are close to each other, which effectively reduce the gap between the adjacent mirrors. The end losses of the receiver are very important, especially in a small-scale collecting system. A movable receiver is introduced for the reduction of the end losses. Moreover, a stretched structure of SPLFR is designed for wind resistance. Finally, the thermal performance of the SPLFR collecting system with fixed and movable receiver located in Guangzhou is tested. The maximum thermal efficiency obtained by this collecting system with movable receiver is 66% which avoid the end losses effectively, and the solar collector thermal loss coefficient is 1.32 W/m"2 °C. The results show that the SPLFR collecting system has excellent thermal performance and a promising application future. Meanwhile, this system will provide a valuable reference for concentrating solar power technology.

  9. Fish assemblages in stream stretches occupied by cattail (Typhaceae, Angiospermae stands in Southeast Brazil

    Directory of Open Access Journals (Sweden)

    Fabíola Carla da Rocha

    Full Text Available Macrophytes are a major component of lentic and lotic aquatic ecosystems. As consequences of environmental degradation, species of cattail (genus Typha may become dominant along streams. The purpose of this study was to investigate the structure and feeding of fish assemblages in stream stretches under influence of Typha sp., also addressing the influences of temporal variation on composition, abundance, biomass, diversity, species richness, and feeding of fish. Six streams (labelled S1-S6 in the upper rio Turvo basin, southeast Brazil, with dense stands of Typha sp. in the instream and riparian habitat, were studied in six campaigns during three central months in both of the dry and wet periods, by using a standardized collection effort. Thirty-seven fish species were registered, totaling 4,228 individuals and 3.9 kg of biomass. Abundance, biomass, diversity, and species richness was higher in the wet period, but only the temporal variation in the species richness revealed to be statistically significant. Cluster analyses with composition and abundance showed little temporal similarity, but indicated two groups of streams (S1-S2-S5 and S3-S4-S6, that were corroborated along the axis 1 of the ordination analysis. Resident species was represented by six species, most of them considered tolerant and generalists. Chironomidae aquatic larvae and detritus were the most important items in the fish diet. These results suggest that the fish populations are opportunistic in exploring stream stretches occupied by cattail.

  10. Theoretical modelling of physiologically stretched vessel in magnetisable stent assisted magnetic drug targeting application

    International Nuclear Information System (INIS)

    Mardinoglu, Adil; Cregg, P.J.; Murphy, Kieran; Curtin, Maurice; Prina-Mello, Adriele

    2011-01-01

    The magnetisable stent assisted magnetic targeted drug delivery system in a physiologically stretched vessel is considered theoretically. The changes in the mechanical behaviour of the vessel are analysed under the influence of mechanical forces generated by blood pressure. In this 2D mathematical model a ferromagnetic, coiled wire stent is implanted to aid collection of magnetic drug carrier particles in an elastic tube, which has similar mechanical properties to the blood vessel. A cyclic mechanical force is applied to the elastic tube to mimic the mechanical stress and strain of both the stent and vessel while in the body due to pulsatile blood circulation. The magnetic dipole-dipole and hydrodynamic interactions for multiple particles are included and agglomeration of particles is also modelled. The resulting collection efficiency of the mathematical model shows that the system performance can decrease by as much as 10% due to the effects of the pulsatile blood circulation. - Research highlights: →Theoretical modelling of magnetic drug targeting on a physiologically stretched stent-vessel system. →Cyclic mechanical force applied to mimic the mechanical stress and strain of both stent and vessel. →The magnetic dipole-dipole and hydrodynamic interactions for multiple particles is modelled. →Collection efficiency of the mathematical model is calculated for different physiological blood flow and magnetic field strength.

  11. Touch Locating and Stretch Sensing Studies of Conductive Hydrogels with Applications to Soft Robots.

    Science.gov (United States)

    Zhou, Yanmin; He, Bin; Yan, Zhe; Shang, Yinghui; Wang, Qigang; Wang, Zhipeng

    2018-02-13

    Soft robots possess great potential in environmental adaptations, while their environmental sensing abilities are critical. Conductive hydrogels have been suggested to possess sensing abilities. However, their application in soft robots is lacking. In this work, we fabricated a soft and stretchable gel material, introduced its sensing mechanisms, and developed a measurement setup. Both experimental and simulation studies indicate strong nonlinearity of touch locating on a square touch panel with Cartesian coordinates. To simplify the touch locating, we proposed a touch locating system based on round touch panels with polar coordinates. Mathematical calculations and finite element method (FEM) simulations showed that in this system the locating of a touch point was only determined by its polar radius. This was verified by experimental studies. As a resistor, a gel strip's resistance increases with stretching. To demonstrate their applications on soft robots, a 3D printed three-fingered soft gripper was employed with gel strips attached. During finger bending for rod grasping, the resistances of the gel strips increased, indicating stretching of the soft material. Furthermore, the strain and stress of a gel strip increased with a decrease of the rod diameter. These studies advance the application of conductive hydrogels on soft robots.

  12. Barcoded pyrosequencing analysis of the microbial community in a simulator of the human gastrointestinal tract showed a colon region-specific microbiota modulation for two plant-derived polysaccharide blends.

    Science.gov (United States)

    Marzorati, Massimo; Maignien, Lois; Verhelst, An; Luta, Gabriela; Sinnott, Robert; Kerckhof, Frederiek Maarten; Boon, Nico; Van de Wiele, Tom; Possemiers, Sam

    2013-02-01

    The combination of a Simulator of the Human Intestinal Microbial Ecosystem with ad hoc molecular techniques (i.e. pyrosequencing, denaturing gradient gel electrophoresis and quantitative PCR) allowed an evaluation of the extent to which two plant polysaccharide supplements could modify a complex gut microbial community. The presence of Aloe vera gel powder and algae extract in product B as compared to the standard blend (product A) improved its fermentation along the entire simulated colon. The potential extended effect of product B in the simulated distal colon, as compared to product A, was confirmed by: (i) the separate clustering of the samples before and after the treatment in the phylogenetic-based dendrogram and OTU-based PCoA plot only for product B; (ii) a higher richness estimator (+33 vs. -36 % of product A); and (iii) a higher dynamic parameter (21 vs. 13 %). These data show that the combination of well designed in vitro simulators with barcoded pyrosequencing is a powerful tool for characterizing changes occurring in the gut microbiota following a treatment. However, for the quantification of low-abundance species-of interest because of their relationship to potential positive health effects (i.e. bifidobacteria or lactobacilli)-conventional molecular ecological approaches, such as PCR-DGGE and qPCR, still remain a very useful complementary tool.

  13. Intraplaque stretch in carotid atherosclerotic plaque--an effective biomechanical predictor for subsequent cerebrovascular ischemic events.

    Directory of Open Access Journals (Sweden)

    Zhongzhao Teng

    Full Text Available BACKGROUND: Stretch is a mechanical parameter, which has been proposed previously to affect the biological activities in different tissues. This study explored its utility in determining plaque vulnerability. METHODS: One hundred and six patients with mild to moderate carotid stenosis were recruited in this study (53 symptomatic and 53 asymptomatic. High resolution, multi-sequence magnetic resonance (MR imaging was performed to delineate various plaque components. Finite element method was used to predict high stretch concentration within the plaque. RESULTS: During a two-year follow-up, 11 patients in symptomatic group and 3 in asymptomatic group experienced recurrent cerebrovascular events. Plaque stretch at systole and stretch variation during one cardiac cycle was greater in symptomatic group than those in the asymptomatic. Within the symptomatic group, a similar trend was observed in patients with recurrent events compared to those without. CONCLUSION: Plaques with high stretch concentration and large stretch variation are associated with increased risk of future cerebrovascular events.

  14. Structural Studies of Three-Arm Star Block Copolymers Exposed to Extreme Stretch Suggests a Persistent Polymer Tube

    Science.gov (United States)

    Mortensen, Kell; Borger, Anine L.; Kirkensgaard, Jacob J. K.; Garvey, Christopher J.; Almdal, Kristoffer; Dorokhin, Andriy; Huang, Qian; Hassager, Ole

    2018-05-01

    We present structural small-angle neutron scattering studies of a three-armed polystyrene star polymer with short deuterated segments at the end of each arm. We show that the form factor of the three-armed star molecules in the relaxed state agrees with that of the random phase approximation of Gaussian chains. Upon exposure to large extensional flow conditions, the star polymers change conformation resulting in a highly stretched structure that mimics a fully extended three-armed tube model. All three arms are parallel to the flow, one arm being either in positive or negative stretching direction, while the two other arms are oriented parallel, right next to each other in the direction opposite to the first arm.

  15. Modified Fourier heat flux on MHD flow over stretched cylinder filled with dust, Graphene and silver nanoparticles

    Directory of Open Access Journals (Sweden)

    S. Mamatha Upadhya

    2018-06-01

    Full Text Available A Comprehensive study on laminar, magnetohydrodynamic (MHD boundary layer flow of nanofluid (water + Silver, water + Graphene embedded with conducting micrometer sized dust particles over a stretching cylinder with the incorporation of Cattaneo-Christov heat flux model is conducted. Appropriate similarity variables are employed to the flow governing equations and the resulting ordinary differential equations are solved by employing Runge-Kutta-Fehlberg method. The results for varied controlling parameters for both dusty nano fluid and dust phase are shown through graphs, table and discussed in detail. Authentication of the obtained results is provided by comparing with published results. Results indicate that Graphene + water dusty nanofluid shows better heat transfer performance compared with Silver + water dusty nanofluid. Improvement in thermal relaxation boosts temperature distribution in both fluid and dust phase. Keywords: Graphene nano particles, Silver nano particles, Stretching cylinder, Dusty fluid, Cattaneo-Christov heat flux, MHD

  16. Failure prediction for the optimization of stretch forming aluminium-polymer laminate foils used for pharmaceutical packaging

    Science.gov (United States)

    Müller, Simon; Weygand, Sabine M.

    2018-05-01

    Axisymmetric stretch forming processes of aluminium-polymer laminate foils (e.g. consisting of PA-Al-PVC layers) are analyzed numerically by finite element modeling of the multi-layer material as well as experimentally in order to identify a suitable damage initiation criterion. A simple ductile fracture criterion is proposed to predict the forming limits. The corresponding material constants are determined from tensile tests and then applied in forming simulations with different punch geometries. A comparison between the simulations and the experimental results shows that the determined failure constants are not applicable. Therefore, one forming experiment was selected and in the corresponding simulation the failure constant was fitted to its measured maximum stretch. With this approach it is possible to predict the forming limit of the laminate foil with satisfying accuracy for different punch geometries.

  17. Lewis lung carcinoma regulation of mechanical stretch-induced protein synthesis in cultured myotubes.

    Science.gov (United States)

    Gao, Song; Carson, James A

    2016-01-01

    Mechanical stretch can activate muscle and myotube protein synthesis through mammalian target of rapamycin complex 1 (mTORC1) signaling. While it has been established that tumor-derived cachectic factors can induce myotube wasting, the effect of this catabolic environment on myotube mechanical signaling has not been determined. We investigated whether media containing cachectic factors derived from Lewis lung carcinoma (LLC) can regulate the stretch induction of myotube protein synthesis. C2C12 myotubes preincubated in control or LLC-derived media were chronically stretched. Protein synthesis regulation by anabolic and catabolic signaling was then examined. In the control condition, stretch increased mTORC1 activity and protein synthesis. The LLC treatment decreased basal mTORC1 activity and protein synthesis and attenuated the stretch induction of protein synthesis. LLC media increased STAT3 and AMP-activated protein kinase phosphorylation in myotubes, independent of stretch. Both stretch and LLC independently increased ERK1/2, p38, and NF-κB phosphorylation. In LLC-treated myotubes, the inhibition of ERK1/2 and p38 rescued the stretch induction of protein synthesis. Interestingly, either leukemia inhibitory factor or glycoprotein 130 antibody administration caused further inhibition of mTORC1 signaling and protein synthesis in stretched myotubes. AMP-activated protein kinase inhibition increased basal mTORC1 signaling activity and protein synthesis in LLC-treated myotubes, but did not restore the stretch induction of protein synthesis. These results demonstrate that LLC-derived cachectic factors can dissociate stretch-induced signaling from protein synthesis through ERK1/2 and p38 signaling, and that glycoprotein 130 signaling is associated with the basal stretch response in myotubes. Copyright © 2016 the American Physiological Society.

  18. p38 mitogen-activated protein kinase up-regulates NF-κB transcriptional activation through RelA phosphorylation during stretch-induced myogenesis

    International Nuclear Information System (INIS)

    Ji, Guoping; Liu, Dongxu; Liu, Jing; Gao, Hui; Yuan, Xiao; Shen, Gang

    2010-01-01

    p38 MAPK and nuclear factor-B (NF-B) signaling pathways play an indispensable role in the control of skeletal myogenesis. The specific contribution of these signaling pathways to the response of myoblast to the mechanical stimulation and the molecular mechanisms underlying this response remain unresolved. Using an established in vitro model, we now show that p38 MAP kinase activity regulates the transcriptional activation of NF-κB in response to mechanical stimulation of myoblasts. Furthermore, SB203580 blocked stretch-induced NF-κB activation during myogenesis, not through down-regulation of degradation of IκB-α, and consequent translocation of the p65 subunit of NF-κB to the nucleus. It is likely that stretch-induced NF-κB activation by phosphorylation of p65 NF-κB. Moreover, depletion of p38α using siRNA significantly reduces stretch-induced phosphorylation of RelA and NF-κB activity. These results provides the first evidence of a cross-talk between p38 MAPK and NF-κB signaling pathways during stretch-induced myogenesis, with phosphorylation of RelA being one of the effectors of this promyogenic mechanism. The α isoform of p38MAP kinase regulates the transcriptional activation of NF-κB following stimulation with cyclic stretch.

  19. p38 mitogen-activated protein kinase up-regulates NF-{kappa}B transcriptional activation through RelA phosphorylation during stretch-induced myogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Guoping [Department of Orthodontics, College of Stomatology, Ninth People' s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Research Institute of Stomatology, Shanghai 200011 (China); Liu, Dongxu [Department of Orthodontics, College of Stomatology, Shandong University, Jinan, Shandong Province 250012 (China); Liu, Jing [Department of Orthodontics, The Affiliated Qingdao Municipal Hospital, Qingdao University, Qingdao, Shandong Province 266075 (China); Gao, Hui [Department of Orthodontics, Tianjin Stomatological Hospital, Tianjin 300041 (China); Yuan, Xiao, E-mail: yuanxiaoqd@163.com [Department of Orthodontics, The Affiliated Qingdao Municipal Hospital, Qingdao University, Qingdao, Shandong Province 266075 (China); Shen, Gang, E-mail: ganshen2007@163.com [Department of Orthodontics, College of Stomatology, Ninth People' s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Research Institute of Stomatology, Shanghai 200011 (China)

    2010-01-01

    p38 MAPK and nuclear factor-B (NF-B) signaling pathways play an indispensable role in the control of skeletal myogenesis. The specific contribution of these signaling pathways to the response of myoblast to the mechanical stimulation and the molecular mechanisms underlying this response remain unresolved. Using an established in vitro model, we now show that p38 MAP kinase activity regulates the transcriptional activation of NF-{kappa}B in response to mechanical stimulation of myoblasts. Furthermore, SB203580 blocked stretch-induced NF-{kappa}B activation during myogenesis, not through down-regulation of degradation of I{kappa}B-{alpha}, and consequent translocation of the p65 subunit of NF-{kappa}B to the nucleus. It is likely that stretch-induced NF-{kappa}B activation by phosphorylation of p65 NF-{kappa}B. Moreover, depletion of p38{alpha} using siRNA significantly reduces stretch-induced phosphorylation of RelA and NF-{kappa}B activity. These results provides the first evidence of a cross-talk between p38 MAPK and NF-{kappa}B signaling pathways during stretch-induced myogenesis, with phosphorylation of RelA being one of the effectors of this promyogenic mechanism. The {alpha} isoform of p38MAP kinase regulates the transcriptional activation of NF-{kappa}B following stimulation with cyclic stretch.

  20. Mechanical response of human female breast skin under uniaxial stretching.

    Science.gov (United States)

    Kumaraswamy, N; Khatam, Hamed; Reece, Gregory P; Fingeret, Michelle C; Markey, Mia K; Ravi-Chandar, Krishnaswamy

    2017-10-01

    Skin is a complex material covering the entire surface of the human body. Studying the mechanical properties of skin to calibrate a constitutive model is of great importance to many applications such as plastic or cosmetic surgery and treatment of skin-based diseases like decubitus ulcers. The main objective of the present study was to identify and calibrate an appropriate material constitutive model for skin and establish certain universal properties that are independent of patient-specific variability. We performed uniaxial tests performed on breast skin specimens freshly harvested during mastectomy. Two different constitutive models - one phenomenological and another microstructurally inspired - were used to interpret the mechanical responses observed in the experiments. Remarkably, we found that the model parameters that characterize dependence on previous maximum stretch (or preconditioning) exhibited specimen-independent universal behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Centrifugal stretching along the ground state band of 168Hf

    International Nuclear Information System (INIS)

    Costin, A.; Pietralla, N.; Reese, M.; Moeller, O.; Ai, H.; Casten, R. F.; Heinz, A.; McCutchan, E. A.; Meyer, D. A.; Qian, J.; Werner, V.; Dusling, K.; Fitzpatrick, C. R.; Guerdal, G.; Petkov, P.; Rainovski, G.

    2009-01-01

    The lifetimes of the J π =4 + , 6 + , 8 + , and 10 + levels along the ground state band in 168 Hf were measured by means of the recoil distance Doppler shift (RDDS) method using the New Yale Plunger Device (NYPD) and the SPEEDY detection array at Wright Nuclear Structure Laboratory of Yale University. Excited states in 168 Hf were populated using the 124 Sn( 48 Ti,4n) fusion evaporation reaction. The new lifetime values are sufficiently precise to clearly prove the increase of quadrupole deformation as a function of angular momentum in the deformed nucleus 168 Hf. The data agree with the predictions from the geometrical confined β-soft (CBS) rotor model that involves centrifugal stretching in a soft potential

  2. Stretching a semiflexible polymer with orientation-dependent interactions

    International Nuclear Information System (INIS)

    Zhen Yi; Vilgis, Thomas A

    2009-01-01

    The mean field variational approach is employed to study the effect of a nematic field and an external constant force field on the elasticity of a semiflexible polymer. In the stationary phase, we obtain the force–extension relationship and calculate the hairpin density of a stretched semiflexible polymer in nematic solvents. The force–extension behavior is found to be controlled by the parameters gl p and gf where g is the strength of the nematic field, l p is the bare persistence length and f is the external force. Several distinct regimes for the elastic response and the hairpin density emerge depending on the value of gl p and gf. Qualitative comparisons between our computation and other theories are presented

  3. Serial casting versus stretching technique to treat knee flexion contracture in children with spina bifida: a comparative study.

    Science.gov (United States)

    Al-Oraibi, S; Tariah, Hashem Abu; Alanazi, Abdullah

    2013-01-01

    Severe knee contractures that develop soon after muscle imbalance may not improve with stretching exercises and splinting. An alternative treatment is serial casting, which has been used to promote increased range of motion. The purpose of this study was to compare the effectiveness of using serial casting and passive stretching approaches to treat knee flexion contracture in children with spina bifida. In a pre/post randomized controlled study, ten participants were included in the serial casting group, while eight participants were included in the passive stretching intervention group. The degree of knee extension was measured at baseline, immediately after intervention, and at a one-year follow-up using a standard goniometer. Both groups showed significant improvements in the degree of flexion contracture at the post-treatment evaluation and the follow-up evaluation. The serial casting group showed significant improvements in knee flexion contracture at the post-treatment evaluation, t (9)=13.4, p casting group compared with passive stretching group in relation to the degree of flexion contracture were found at the immediate post-treatment evaluation, F(1, 15)=246, p=0.0001, and the one-year follow-up evaluation, F (1, 15)=51.5, p=0.0001. The outcomes of this study provide the first evidence that serial casting may be a useful intervention in treating knee flexion contracture in children with spina bifida. However, further investigations into serial casting, as well as investigations into the use of serial casting with other interventions, are warranted.

  4. Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force

    Directory of Open Access Journals (Sweden)

    Leyla Alizadeh Ebadi

    2018-03-01

    Full Text Available The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles’ isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A 5 min jogging; (B 5 min jogging followed by 15 s static stretching; (C 5 min jogging followed by 30 s static stretching; (D 5 min jogging, followed by static stretching for 45 s. Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

  5. Effect of Ankle Positioning During Hamstring Stretches for Improving Straight Leg Hip Flexion Motion.

    Science.gov (United States)

    Laudner, Kevin G; Benjamin, Peter J; Selkow, Noelle M

    2016-03-01

    To compare the effects of stretching the hamstrings with the ankle in either a plantar-flexed (PF) or dorsiflexed (DF) position for improving straight leg hip flexion range of motion (ROM) over a 4-week period. Randomized, single-blinded, pretest, posttest design. Athletic training facility. Each limb of 34 asymptomatic individuals (15 males, 19 females) was randomly assigned to one of the 3 groups. Twenty-four limbs received hamstring stretches with the ankle in DF, 24 limbs received hamstring stretches with the ankle in PF, and 20 limbs received no stretch (control). Ankle position (PF, DF) during hamstring stretching. We measured pretest and posttest passive straight leg hip flexion ROM with the test ankle in a neutral position. For the intervention groups, the test limb was passively stretched with the ankle held in end range DF or PF for their respective group. Each stretch was held for 30 seconds for a total of 3 applications. Two treatment sessions were completed per week for a total of 4 weeks. The control limbs received no stretching during the 4-week period. We conducted 1-way analyses of covariance to determine significant changes in ROM between groups (P hamstrings in either PF or DF improve straight leg hip ROM compared with a control group. The results of this study should be considered by clinicians when determining the optimal stretching techniques aimed at increasing hamstring length.

  6. ACUTE EFFECTS OF THREE DIFFERENT STRETCHING PROTOCOLS ON THE WINGATE TEST PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Bruno L. Franco

    2012-03-01

    Full Text Available The purpose of this study was to examine the acute effects of different stretching exercises on the performance of the traditional Wingate test (WT. Fifteen male participants performed five WT; one for familiarization (FT, and the remaining four after no stretching (NS, static stretching (SS, dynamic stretching (DS, and proprioceptive neuromuscular facilitation (PNF. Stretches were targeted for the hamstrings, quadriceps, and calf muscles. Peak power (PP, mean power (MP, and the time to reach PP (TP were calculated. The MP was significantly lower when comparing the DS (7.7 ± 0.9 W/kg to the PNF (7.3 ± 0.9 W/kg condition (p < 0.05. For PP, significant differences were observed between more comparisons, with PNF stretching providing the lowest result. A consistent increase of TP was observed after all stretching exercises when compared to NS. The results suggest the type of stretching, or no stretching, should be considered by those who seek higher performance and practice sports that use maximal anaerobic power.

  7. 600 Volt Stretched Lens Array for Solar Electric Propulsion, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — ENTECH, Auburn, NASA, and others have recently developed a new space photovoltaic array called the Stretched Lens Array (SLA), offering unprecedented performance...

  8. EFFECTS OF DYNAMIC AND STATIC STRETCHING WITHIN GENERAL AND ACTIVITY SPECIFIC WARM-UP PROTOCOLS

    Directory of Open Access Journals (Sweden)

    Michael Samson

    2012-06-01

    Full Text Available The purpose of the study was to determine the effects of static and dynamic stretching protocols within general and activity specific warm-ups. Nine male and ten female subjects were tested under four warm-up conditions including a 1 general aerobic warm-up with static stretching, 2 general aerobic warm-up with dynamic stretching, 3 general and specific warm-up with static stretching and 4 general and specific warm-up with dynamic stretching. Following all conditions, subjects were tested for movement time (kicking movement of leg over 0.5 m distance, countermovement jump height, sit and reach flexibility and 6 repetitions of 20 metre sprints. Results indicated that when a sport specific warm-up was included, there was an 0.94% improvement (p = 0.0013 in 20 meter sprint time with both the dynamic and static stretch groups. No such difference in sprint performance between dynamic and static stretch groups existed in the absence of the sport specific warm-up. The static stretch condition increased sit and reach range of motion (ROM by 2.8% more (p = 0.0083 than the dynamic condition. These results would support the use of static stretching within an activity specific warm-up to ensure maximal ROM along with an enhancement in sprint performance

  9. Implementation of a controller for linear positioners applicable in optical fiber stretching

    International Nuclear Information System (INIS)

    Castrillo Piedra, Andres Rodolfo

    2014-01-01

    A low cost controller is implemented for linear positioners applicable in optic fiber stretching. The possibility of using a donated equipment is evaluated by the Escuela de Ingenieria Mecanica. The equipment is required by the non-linear photonic research laboratory (NLPR-LAB) for stretching of micro structured fiber. The process has required a slow and precise stretching, so the controllers must be precisely programmed to rotate the motors at different speeds. Donated equipment is evaluated to see if it is possible to use for fiber stretching [es

  10. Pion scattering to 8- stretched states in 60Ni

    International Nuclear Information System (INIS)

    Clausen, B.L.

    1988-03-01

    Using the Energetic Pion Channel and Spectrometer at the Los Alamos Meson Physics Facility, differential cross sections for pion scattering were measured for ten previously known J/sup π/ = 8/sup /minus// stretched states in 60 Ni. A possible new pure isoscalar stretched state was also found. The data were taken near the /DELTA//sub 3,3/-resonance using 162 MeV incident pions and scattering angles of 65/degree/, 80/degree/, and 90/degree/ for π + and 65/degree/ and 80/degree/ for π/sup /minus//. The analysis of the 60 Ni data found that the use of Woods-Saxon wave functions in the theoretical calculations gave much better agreement with data than the use of the usual harmonic oscillator wave functions. The WS theory gave better predictions of: the angle at which the π/sup /minus// and π + angular distributions are maximum, the ratios of π/sup /minus// to π + cross sections for pure isovector states (which were much larger than unity), and the absolute size of the cross sections for all states (so that the normalization factor necessary to arrive at agreement of theory with data was closer to unity). The theoretical calculations used the distorted wave impulse approximation, including new methods for unbound states. The sensitivities of the calculations to input parameters were investigated. This analysis using WS wave functions was extended to five other nuclei ( 12 C, 14 C, 16 O, 28 Si, and 54 Fe) on which both pion scattering and electron scattering have been done. A significant improvement in arriving at a normalization factor close to unity was found when WS wave functions were consistently used for analyzing both pion and electron inelastic scattering data. 101 refs., 26 figs., 13 tabs

  11. Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

    Science.gov (United States)

    Reschke, M. F.; Wood, S. J.; Cerisano, J. M.; Kofman, I. S.; Fisher, E. A.; Esteves, J. T.; Taylor, L. C.; DeDios, Y. E.; Harm, D. L.

    2011-01-01

    rest period, with a return to baseline 3 to 5 days after bed rest, depending on the duration of bed rest. In addition, a relationship between CV and loss of muscle strength in the lower leg was observed post bed rest for most subjects. Immediately post-bed rest, most subjects showed decreased performance on SOTs, with the greater decrements on sway-referenced support and head movement conditions. Post-bed rest decrements were less than typically observed following spaceflight. Decrements in postural control and the stretch reflex can be primarily attributed to the unloading mechanisms this ground-based analog provides. The stretch reflex is a concise test measurement that can be obtained during the head-down phase of bed rest, as it does not interfere with the bed rest paradigm. This makes it an ideal tool that can detect, early on, whether a countermeasure is successful in preserving muscle function.

  12. Flame-Vortex Interactions Imaged in Microgravity - To Assess the Theory Flame Stretch

    Science.gov (United States)

    Driscoll, James F.

    2001-01-01

    The goals of this research are to: 1) Assess the Theory of Flame Stretch by operating a unique flame-vortex experiment under microgravity conditions in the NASA Glenn 2.2 Second Drop Tower (drops to identify operating conditions have been completed); 2) Obtain high speed shadowgraph images (500-1000 frames/s) using the drop rig (images were obtained at one-g, and the NASA Kodak RO camera is being mounted on the drop rig); 3) Obtain shadowgraph and PIV images at 1-g while varying the effects of buoyancy by controlling the Froude number (completed); 4) Numerically model the inwardly-propagating spherical flame that is observed in the experiment using full chemistry and the RUN 1DL code (completed); 5) Send images of the flame shape to Dr. G. Patniak at NRL who is numerically simulating the entire flame-vortex interaction of the present experiment (data transfer completed); and 6) Assess the feasibility of obtaining PIV velocity field images in the drop rig, which would be useful (but not required) for our assessment of the Theory of Flame Stretch (PIV images were obtained at one-g using same low laser power that is available from fiber optic cable in drop tower). The motivation for the work is to obtain novel measurement needed to develop a physically accurate model of turbulent combustion that can help in the control of engine pollutants. The unique experiment allows, for the first time, the detailed study of a negatively-curved (negatively stretched) flame, which is one of the five fundamental types of premixed flames. While there have been studies of flat flames, positively-curved (outwardly-propagating) cases and positively-strained (counterflow) cases, this is the first detailed study of a negatively-curved (inwardly-propagating) flame. The first set of drops in the 2.2 Second Drop Tower showed that microgravity provides more favorable conditions for achieving inwardly-propagating flames (IPFs) than 1-g. A vortex interacts with a flame and creates a spherical

  13. Experimental quantification of transient stretch effects from vortices interacting with premixed flames

    Science.gov (United States)

    Danby, Sean James

    conducted using non-invasive laser diagnostics, such as particle image velocimetry and planer laser induced fluorescence of the OH radical. The dependence of heat release rate on temperature provides an estimation of the strain rate dependence of the reaction rate. Findings include a direct effect of stretch rate on temperature along the flame reaction zone; however the trend depends on thermo-diffusive stability. For both fuels at a thermo-diffusively unstable mixture, by increasing the vortex strength, the stretch rate increases, while the temperature decreases. The thermo-diffusively stable flames (propane with φ ≤ 1.08) generally show an opposite trend to the unstable flames. By increasing the vortex strength, the thermo-diffusively stable flames tend to have a reduction in stretch rate, which allows an increase in temperature along the flame-vortex interface. Overall, an increase in stretch rate causes all flames to reduce the average reaction zone temperature regardless of thermo-diffusive stability. The formation of surface structure corrugation in thermo-diffusively unstable flames requires an external (to the flame) perturbation. This perturbation is generally in the form heat loss due to either a high stretch rate from an aerodynamic perturbation (vortex) or a localized thermodynamic heat sink (electrodes).

  14. MULLIGAN MOBILIZATION VERSUS STRETCHING ON THE MANAGEMENT OF PIRIFORMIS SYNDROME A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Samahir Abuaraki Elbkheet

    2016-04-01

    Full Text Available Background: Piriformis syndrome is a commonly overlooked specific cause of low back pain. Apart from mimicking the sciatica-like symptoms, unilateral piriformis tightness can cause rotational dysfunction and pain in the lumbar region. This could lead to low back pain which is a common musculo skeletal problem and a major reason for activity limitation. Stretching the piriformis tightened muscle is a preferred choice of treatment against surgical intervention to release the muscle. Mulligan’s mobilization is based on movement with mobilization which is proven to be effective in many musculo skeletal dysfunctions including the lumbar spine. The purpose of this study is to explore and compare the two treatment methods in relieving the low back pain in clinical conditions with piriformis syndrome. Methods: In this experimental study, 40 patients with piriformis syndrome were selected and divided into two groups. One group was given only piriformis stretching for the tightened muscle and the other group given Mulligan mobilization for lumbo sacral joints. VAS and lower limb functional index were taken to compare before and after the treatment regime of 4 weeks. Results: There was no significant difference between the two groups in both pain scale and lower limb mobility and function. But there was significant improvement in pain relief and LLFI after the treatment regime in both groups compared to the pre-treatment status. Conclusion: Even as the piriformis syndrome is caused by the tightness of the muscle, the consequence in the lower back and lumbar spine mobility can be improved by a Mulligan mobilization as a single mode of intervention.

  15. Cleavage strain in the Variscan fold belt, County Cork, Ireland, estimated from stretched arsenopyrite rosettes

    Science.gov (United States)

    Ford, M.; Ferguson, C.C.

    1985-01-01

    In south-west Ireland, hydrothermally formed arsenopyrite crystals in a Devonian mudstone have responded to Variscan deformation by brittle extension fracture and fragment separation. The interfragment gaps and terminal extension zones of each crystal are infilled with fibrous quartz. Stretches within the cleavage plane have been calculated by the various methods available, most of which can be modified to incorporate terminal extension zones. The Strain Reversal Method is the most accurate currently available but still gives a minimum estimate of the overall strain. The more direct Hossain method, which gives only slightly lower estimates with this data, is more practical for field use. A strain ellipse can be estimated from each crystal rosette composed of three laths (assuming the original interlimb angles were all 60??) and, because actual rather than relative stretches are estimated, this provides a lower bound to the area increase in the plane of cleavage. Based on the average of our calculated strain ellipses this area increase is at least 114% and implies an average shortening across the cleavage of at least 53%. However, several lines of evidence suggest that the cleavage deformation was more intense and more oblate than that calculated, and we argue that a 300% area increase in the cleavage plane and 75% shortening across the cleavage are more realistic estimates of the true strain. Furthermore, the along-strike elongation indicated is at least 80%, which may be regionally significant. Estimates of orogenic contraction derived from balanced section construction should therefore take into account the possibility of a substantial strike elongation, and tectonic models that can accommodate such elongations need to be developed. ?? 1985.

  16. Exercise, especially combined stretching and strengthening exercise, reduces myofascial pain: a systematic review

    Directory of Open Access Journals (Sweden)

    Juliano Bergamaschine Mata Diz

    2017-01-01

    Full Text Available Question: Among people with myofascial pain, does exercise reduce the intensity of the pain and disability? Design: Systematic review of randomised and quasi-randomised controlled trials. Participants: People with myofascial pain of any duration. Intervention: Exercise versus minimal or no intervention and exercise versus other intervention. Outcome measures: Pain intensity and disability. Results: Eight studies involving 255 participants were included. Pooled estimates from six studies showed statistically significant effects of exercise when compared with minimal or no intervention (support and encouragement or no treatment on pain intensity at short-term follow-up. The weighted mean difference in pain intensity due to exercise was –1.2 points (95% CI –2.3 to –0.1 on a 0 to 10 scale. Pooled estimates from two studies showed a non-significant effect of exercise when compared with other interventions (electrotherapy or dry needling on pain intensity at short-term follow-up. The weighted mean difference in pain intensity due to exercise instead of other therapies was 0.4 points (95% CI –0.3 to 1.1 on a 0 to 10 scale. Individual studies reported no significant effects of exercise on disability compared with minimal intervention (–0.4, 95% CI –1.3 to 0.5 and other interventions (0.0, 95% CI –0.8 to 0.8 at short-term follow-up. Sensitivity analysis suggested that combining stretching and strengthening achieves greater short-term effects on pain intensity compared with minimal or no intervention (–2.3, 95% CI –4.1 to –0.5. Conclusion: Evidence from a limited number of trials indicates that exercise has positive small-to-moderate effects on pain intensity at short-term follow-up in people with myofascial pain. A combination of stretching and strengthening exercises seems to achieve greater effects. These estimates may change with future high-quality studies. [Mata Diz JB, de Souza JRLM, Leopoldino AAO, Oliveira VC (2016 Exercise

  17. Examining flow-flame interaction and the characteristic stretch rate in vortex-driven combustion dynamics using PIV and numerical simulation

    KAUST Repository

    Hong, Seunghyuck; Speth, Raymond L.; Shanbhogue, Santosh J.; Ghoniem, Ahmed F.

    2013-01-01

    In this paper, we experimentally investigate the combustion dynamics in lean premixed flames in a laboratory scale backward-facing step combustor in which flame-vortex driven dynamics are observed. A series of tests was conducted using propane/hydrogen/air mixtures for various mixture compositions at the inlet temperature ranging from 300K to 500K and at atmospheric pressure. Pressure measurements and high speed particle image velocimetry (PIV) are used to generate pressure response curves and phase-averaged vorticity and streamlines as well as the instantaneous flame front, respectively, which describe unsteady flame and flow dynamics in each operating regime. This work was motivated in part by our earlier study where we showed that the strained flame consumption speed Sc can be used to collapse the pressure response curves over a wide range of operating conditions. In previous studies, the stretch rate at which Sc was computed was determined by trial and error. In this study, flame stretch is estimated using the instantaneous flame front and velocity field from the PIV measurement. Independently, we also use computed strained flame speed and the experimental data to determine the characteristic values of stretch rate near the mode transition points at which the flame configuration changes. We show that a common value of the characteristic stretch rate exists across all the flame configurations. The consumption speed computed at the characteristic stretch rate captures the impact of different operating parameters on the combustor dynamics. These results suggest that the unsteady interactions between the turbulent flow and the flame dynamics can be encapsulated in the characteristic stretch rate, which governs the critical flame speed at the mode transitions and thereby plays an important role in determining the stability characteristics of the combustor. © 2013 The Combustion Institute.

  18. Examining flow-flame interaction and the characteristic stretch rate in vortex-driven combustion dynamics using PIV and numerical simulation

    KAUST Repository

    Hong, Seunghyuck

    2013-08-01

    In this paper, we experimentally investigate the combustion dynamics in lean premixed flames in a laboratory scale backward-facing step combustor in which flame-vortex driven dynamics are observed. A series of tests was conducted using propane/hydrogen/air mixtures for various mixture compositions at the inlet temperature ranging from 300K to 500K and at atmospheric pressure. Pressure measurements and high speed particle image velocimetry (PIV) are used to generate pressure response curves and phase-averaged vorticity and streamlines as well as the instantaneous flame front, respectively, which describe unsteady flame and flow dynamics in each operating regime. This work was motivated in part by our earlier study where we showed that the strained flame consumption speed Sc can be used to collapse the pressure response curves over a wide range of operating conditions. In previous studies, the stretch rate at which Sc was computed was determined by trial and error. In this study, flame stretch is estimated using the instantaneous flame front and velocity field from the PIV measurement. Independently, we also use computed strained flame speed and the experimental data to determine the characteristic values of stretch rate near the mode transition points at which the flame configuration changes. We show that a common value of the characteristic stretch rate exists across all the flame configurations. The consumption speed computed at the characteristic stretch rate captures the impact of different operating parameters on the combustor dynamics. These results suggest that the unsteady interactions between the turbulent flow and the flame dynamics can be encapsulated in the characteristic stretch rate, which governs the critical flame speed at the mode transitions and thereby plays an important role in determining the stability characteristics of the combustor. © 2013 The Combustion Institute.

  19. Effects of Proprioceptive Neuromuscular Facilitation Stretching and Kinesiology Taping on Pelvic Compensation During Double-Knee Extension

    Directory of Open Access Journals (Sweden)

    Lee Seung-Woong

    2015-12-01

    Full Text Available Shortened hamstrings are likely to restrict the anterior pelvic tilt and induce a slumped posture due to the posterior pelvic tilt. This study was conducted to compare the effects of proprioceptive neuromuscular facilitation (PNF stretching and modified anterior pelvic tilt taping (APTT on hamstring shortness-associated pelvic compensation while executing seated double-knee extension. Male college students (28 healthy young adults; mean age: 21.4 ± 2.1 years with hamstring shortness were recruited as study subjects and randomly assigned to either the PNF stretching group (control group or the APTT group (experimental group. In all the subjects, changes in the movement distance of the centre of gluteal pressure (COGP as well as rectus abdominis (RA and semitendinosus (SEM muscle activities were measured during seated double-knee extension while the respective intervention method was applied. Both groups showed significant decreases in COGP distance and RA muscle activity compared with their respective baseline values (p < 0.05, however, no significant changes were observed in SEM muscle activity. We can infer that not only a direct intervention on the hamstring, such as PNF stretching, but also a modified APTT-mediated pelvic intervention may be used as a method for reducing pelvic compensation induced by hamstring shortness.

  20. Mixed convection flow of couple stress nanofluid over oscillatory stretching sheet with heat absorption/generation effects

    Directory of Open Access Journals (Sweden)

    Sami Ullah Khan

    2018-03-01

    Full Text Available The aim of this article is to highlight the unsteady mixed convective couple stress nanoliquid flow passed through stretching surface. The flow is generated due to periodic oscillations of sheet. An appropriate set of dimensionless variables are used to reduce the independent variables in governing equations arising from mathematical modeling. An analytical solution has been computed by employing the technique of homotopy method. The outcomes of various sundry parameters like couple stress parameter, the ratio of angular velocity to stretching rate, thermophoresis parameter, Hartmann number, Prandtl number, heat source/sink parameter, Schmidt number described graphically and in tabular form. It is observed that the velocity profile increases by increasing mixed convection parameter and concentration buoyancy parameter. The temperature enhances for larger values of Hartmann number and Brownian. The concentration profile increases by increasing thermophoresis parameter. Results show that wall shear stress increases by increasing couple stress parameter and ratio of oscillating frequency to stretching rate. Keywords: Oscillatory surface, Couple stress fluid, Nanoparticles, Heat absorption/generation

  1. Hydrogen-Bonding Network and OH Stretch Vibration of Cellulose: Comparison of Computational Modeling with Polarized IR and SFG Spectra.

    Science.gov (United States)

    Lee, Christopher M; Kubicki, James D; Fan, Bingxin; Zhong, Linghao; Jarvis, Michael C; Kim, Seong H

    2015-12-10

    Hydrogen bonds play critical roles in noncovalent directional interactions determining the crystal structure of cellulose. Although diffraction studies accurately determined the coordinates of carbon and oxygen atoms in crystalline cellulose, the structural information on hydrogen atoms involved in hydrogen-bonding is still elusive. This could be complemented by vibrational spectroscopy; but the assignment of the OH stretch peaks has been controversial. In this study, we performed calculations using density functional theory with dispersion corrections (DFT-D2) for the cellulose Iβ crystal lattices with the experimentally determined carbon and oxygen coordinates. DFT-D2 calculations revealed that the OH stretch vibrations of cellulose are highly coupled and delocalized through intra- and interchain hydrogen bonds involving all OH groups in the crystal. Additionally, molecular dynamics (MD) simulations of a single cellulose microfibril showed that the conformations of OH groups exposed at the microfibril surface are not well-defined. Comparison of the computation results with the experimentally determined IR dichroism of uniaxially aligned cellulose microfibrils and the peak positions of various cellulose crystals allowed unambiguous identification of OH stretch modes observed in the vibrational spectra of cellulose.

  2. Immobilization and therapeutic passive stretching generate thickening and increase the expression of laminin and dystrophin in skeletal muscle

    International Nuclear Information System (INIS)

    Cação-Benedini, L.O.; Ribeiro, P.G.; Prado, C.M.; Chesca, D.L.; Mattiello-Sverzut, A.C.

    2014-01-01

    Extracellular matrix and costamere proteins transmit the concentric, isometric, and eccentric forces produced by active muscle contraction. The expression of these proteins after application of passive tension stimuli to muscle remains unknown. This study investigated the expression of laminin and dystrophin in the soleus muscle of rats immobilized with the right ankle in plantar flexion for 10 days and subsequent remobilization, either by isolated free movement in a cage or associated with passive stretching for up to 10 days. The intensity of the macrophage response was also evaluated. One hundred and twenty-eight female Wistar rats were divided into 8 groups: free for 10 days; immobilized for 10 days; immobilized/free for 1, 3, or 10 days; or immobilized/stretched/free for 1, 3, or 10 days. After the experimental procedures, muscle tissue was processed for immunofluorescence (dystrophin/laminin/CD68) and Western blot analysis (dystrophin/laminin). Immobilization increased the expression of dystrophin and laminin but did not alter the number of macrophages in the muscle. In the stretched muscle groups, there was an increase in dystrophin and the number of macrophages after 3 days compared with the other groups; dystrophin showed a discontinuous labeling pattern, and laminin was found in the intracellular space. The amount of laminin was increased in the muscles treated by immobilization followed by free movement for 10 days. In the initial stages of postimmobilization (1 and 3 days), an exacerbated macrophage response and an increase of dystrophin suggested that the therapeutic stretching technique induced additional stress in the muscle fibers and costameres

  3. Immobilization and therapeutic passive stretching generate thickening and increase the expression of laminin and dystrophin in skeletal muscle

    Energy Technology Data Exchange (ETDEWEB)

    Cação-Benedini, L.O.; Ribeiro, P.G. [Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Medicina e Reabilitação do Aparelho Locomotor, Departamento de Biomecânica, Ribeirão Preto, SP, Brasil, Departamento de Biomecânica, Medicina e Reabilitação do Aparelho Locomotor, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Prado, C.M.; Chesca, D.L. [Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Patologia, Ribeirão Preto, SP, Brasil, Departamento de Patologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Mattiello-Sverzut, A.C. [Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Medicina e Reabilitação do Aparelho Locomotor, Departamento de Biomecânica, Ribeirão Preto, SP, Brasil, Departamento de Biomecânica, Medicina e Reabilitação do Aparelho Locomotor, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2014-05-09

    Extracellular matrix and costamere proteins transmit the concentric, isometric, and eccentric forces produced by active muscle contraction. The expression of these proteins after application of passive tension stimuli to muscle remains unknown. This study investigated the expression of laminin and dystrophin in the soleus muscle of rats immobilized with the right ankle in plantar flexion for 10 days and subsequent remobilization, either by isolated free movement in a cage or associated with passive stretching for up to 10 days. The intensity of the macrophage response was also evaluated. One hundred and twenty-eight female Wistar rats were divided into 8 groups: free for 10 days; immobilized for 10 days; immobilized/free for 1, 3, or 10 days; or immobilized/stretched/free for 1, 3, or 10 days. After the experimental procedures, muscle tissue was processed for immunofluorescence (dystrophin/laminin/CD68) and Western blot analysis (dystrophin/laminin). Immobilization increased the expression of dystrophin and laminin but did not alter the number of macrophages in the muscle. In the stretched muscle groups, there was an increase in dystrophin and the number of macrophages after 3 days compared with the other groups; dystrophin showed a discontinuous labeling pattern, and laminin was found in the intracellular space. The amount of laminin was increased in the muscles treated by immobilization followed by free movement for 10 days. In the initial stages of postimmobilization (1 and 3 days), an exacerbated macrophage response and an increase of dystrophin suggested that the therapeutic stretching technique induced additional stress in the muscle fibers and costameres.

  4. Bifurcation and extinction limit of stretched premixed flames with chain-branching intermediate kinetics and radiative loss

    Science.gov (United States)

    Zhang, Huangwei; Chen, Zheng

    2018-05-01

    Premixed counterflow flames with thermally sensitive intermediate kinetics and radiation heat loss are analysed within the framework of large activation energy. Unlike previous studies considering one-step global reaction, two-step chemistry consisting of a chain branching reaction and a recombination reaction is considered here. The correlation between the flame front location and stretch rate is derived. Based on this correlation, the extinction limit and bifurcation characteristics of the strained premixed flame are studied, and the effects of fuel and radical Lewis numbers as well as radiation heat loss are examined. Different flame regimes and their extinction characteristics can be predicted by the present theory. It is found that fuel Lewis number affects the flame bifurcation qualitatively and quantitatively, whereas radical Lewis number only has a quantitative influence. Stretch rates at the stretch and radiation extinction limits respectively decrease and increase with fuel Lewis number before the flammability limit is reached, while the radical Lewis number shows the opposite tendency. In addition, the relation between the standard flammability limit and the limit derived from the strained near stagnation flame is affected by the fuel Lewis number, but not by the radical Lewis number. Meanwhile, the flammability limit increases with decreased fuel Lewis number, but with increased radical Lewis number. Radical behaviours at flame front corresponding to flame bifurcation and extinction are also analysed in this work. It is shown that radical concentration at the flame front, under extinction stretch rate condition, increases with radical Lewis number but decreases with fuel Lewis number. It decreases with increased radiation loss.

  5. [Effectiveness of a stretching program on anxiety levels of workers in a logistic platform: a randomized controlled study].

    Science.gov (United States)

    Montero-Marín, Jesús; Asún, Sonia; Estrada-Marcén, Nerea; Romero, Rosario; Asún, Roberto

    2013-01-01

    To study the influence of a short programme of stretching exercises on anxiety levels of workers in a Spanish logistic company. A controlled clinical trial was carried out by means of an inter-subject design of random homogeneous blocks. Participants were assigned to the experimental group (n=67), treated with a programme of stretching exercises of 10-minute duration after working hours for a period of 3 months, or to the untreated control group (n=67). The primary result variable was anxiety, and the secondary variables were burnout syndrome, quality of life and flexibility. An analysis of covariance (ANCOVA) by intention to treat was performed on each of the result variables by controlling the baseline scores, the age and the practice of introjective activities outside the program, with the size effect calculated by means of the partial eta-squared value (η(2)). The results of the ANCOVA showed a moderate effect of the stretching exercise programme on the levels of anxiety (η(2)=0,06; P=.004). Other effects found were substantial for flexibility (η(2)=0,13; P<.001); moderately high for bodily pain (η(2)=0,08; P=.001), and moderate for vitality (η(2)=0,05; P=.016); mental health (η(2)=0,05; P=.017); general health (η(2)=0,04; P=.028) and exhaustion (η(2)=0,04; P=.025). The implementation of a short programme of stretching exercises in the work place was effective for reducing levels of anxiety, bodily pain and exhaustion, and for raising levels of vitality, mental health, general health and flexibility. This type of intervention could be seen as a low-cost strategy for improving the well-being of workers. Copyright © 2013 Elsevier España, S.L. All rights reserved.

  6. Doubly stratified MHD tangent hyperbolic nanofluid flow due to permeable stretched cylinder

    Science.gov (United States)

    Nagendramma, V.; Leelarathnam, A.; Raju, C. S. K.; Shehzad, S. A.; Hussain, T.

    2018-06-01

    An investigation is exhibited to analyze the presence of heat source and sink in doubly stratified MHD incompressible tangent hyperbolic fluid due to stretching of cylinder embedded in porous space under nanoparticles. To develop the mathematical model of tangent hyperbolic nanofluid, movement of Brownian and thermophoretic are accounted. The established equations of continuity, momentum, thermal and solutal boundary layers are reassembled into sets of non-linear expressions. These assembled expressions are executed with the help of Runge-Kutta scheme with MATLAB. The impacts of sundry parameters are illustrated graphically and the engineering interest physical quantities like skin friction, Nusselt and Sherwood number are examined by computing numerical values. It is clear that the power-law index parameter and curvature parameter shows favorable effect on momentum boundary layer thickness whereas Weissennberg number reveals inimical influence.

  7. Laboratory Observation of a Plasma-Flow-State Transition from Diverging to Stretching a Magnetic Nozzle.

    Science.gov (United States)

    Takahashi, Kazunori; Ando, Akira

    2017-06-02

    An axial magnetic field induced by a plasma flow in a divergent magnetic nozzle is measured when injecting the plasma flow from a radio frequency (rf) plasma source located upstream of the nozzle. The source is operated with a pulsed rf power of 5 kW, and the high density plasma flow is sustained only for the initial ∼100  μsec of the discharge. The measurement shows a decrease in the axial magnetic field near the source exit, whereas an increase in the field is detected at the downstream side of the magnetic nozzle. These results demonstrate a spatial transition of the plasma-flow state from diverging to stretching the magnetic nozzle, where the importance of both the Alfvén and ion Mach numbers is shown.

  8. Realizing high magnetic moments in fcc Fe nanoparticles through atomic structure stretch

    International Nuclear Information System (INIS)

    Baker, S H; Roy, M; Thornton, S C; Binns, C

    2012-01-01

    We describe the realization of a high moment state in fcc Fe nanoparticles through a controlled change in their atomic structure. Embedding Fe nanoparticles in a Cu 1-x Au x matrix causes their atomic structure to switch from bcc to fcc. Extended x-ray absorption fine structure (EXAFS) measurements show that the structure in both the matrix and the Fe nanoparticles expands as the amount of Au in the matrix is increased, with the data indicating a tetragonal stretch in the Fe nanoparticles. The samples were prepared directly from the gas phase by co-deposition, using a gas aggregation source and MBE-type sources respectively for the nanoparticle and matrix materials. The structure change in the Fe nanoparticles is accompanied by a sharp increase in atomic magnetic moment, ultimately to values of ∼2.5 ± 0.3 μ B /atom. (paper)

  9. Acute effects of 15min static or contract-relax stretching modalities on plantar flexors neuromuscular properties.

    Science.gov (United States)

    Babault, Nicolas; Kouassi, Blah Y L; Desbrosses, Kevin

    2010-03-01

    The present study aimed to investigate the immediate effects of 15 min static or sub-maximal contract-relax stretching modalities on the neuromuscular properties of plantar flexor muscles. Ten male volunteers were tested before and immediately after 15 min static or contract-relax stretching programs of plantar flexor muscles (20 stretches). Static stretching consisted in 30s stretches to the point of discomfort. For the contract-relax stretching modality, subjects performed 6s sub-maximal isometric plantar flexion before 24s static stretches. Measurements included maximal voluntary isometric torque (MVT) and the corresponding electromyographic activity of soleus (SOL) and medial gastrocnemius (MG) muscles (RMS values), as well as maximal peak torque (Pt) elicited at rest by single supramaximal electrical stimulation of the tibial nerve. After 15 min stretching, significant MVT and SOL RMS decreases were obtained (-6.9+/-11.6% and -6.5+/-15.4%, respectively). No difference was obtained between stretching modalities. Pt remained unchanged after stretching. MG RMS changes were significantly different between stretching modalities (-9.4+/-18.3% and +3.5+/-11.6% after static and contract-relax stretching modalities, respectively). These findings indicated that performing 15 min static or contract-relax stretching had detrimental effects on the torque production capacity of plantar flexor muscles and should be precluded before competition. Mechanisms explaining this alteration seemed to be stretch modality dependent. Copyright 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  10. Breast lesion characterization using whole-lesion histogram analysis with stretched-exponential diffusion model.

    Science.gov (United States)

    Liu, Chunling; Wang, Kun; Li, Xiaodan; Zhang, Jine; Ding, Jie; Spuhler, Karl; Duong, Timothy; Liang, Changhong; Huang, Chuan

    2018-06-01

    Diffusion-weighted imaging (DWI) has been studied in breast imaging and can provide more information about diffusion, perfusion and other physiological interests than standard pulse sequences. The stretched-exponential model has previously been shown to be more reliable than conventional DWI techniques, but different diagnostic sensitivities were found from study to study. This work investigated the characteristics of whole-lesion histogram parameters derived from the stretched-exponential diffusion model for benign and malignant breast lesions, compared them with conventional apparent diffusion coefficient (ADC), and further determined which histogram metrics can be best used to differentiate malignant from benign lesions. This was a prospective study. Seventy females were included in the study. Multi-b value DWI was performed on a 1.5T scanner. Histogram parameters of whole lesions for distributed diffusion coefficient (DDC), heterogeneity index (α), and ADC were calculated by two radiologists and compared among benign lesions, ductal carcinoma in situ (DCIS), and invasive carcinoma confirmed by pathology. Nonparametric tests were performed for comparisons among invasive carcinoma, DCIS, and benign lesions. Comparisons of receiver operating characteristic (ROC) curves were performed to show the ability to discriminate malignant from benign lesions. The majority of histogram parameters (mean/min/max, skewness/kurtosis, 10-90 th percentile values) from DDC, α, and ADC were significantly different among invasive carcinoma, DCIS, and benign lesions. DDC 10% (area under curve [AUC] = 0.931), ADC 10% (AUC = 0.893), and α mean (AUC = 0.787) were found to be the best metrics in differentiating benign from malignant tumors among all histogram parameters derived from ADC and α, respectively. The combination of DDC 10% and α mean , using logistic regression, yielded the highest sensitivity (90.2%) and specificity (95.5%). DDC 10% and α mean derived from

  11. STRETCHING EXERCISES - EFFECT ON PASSIVE EXTENSIBILITY AND STIFFNESS IN SHORT HAMSTRINGS OF HEALTHY-SUBJECTS

    NARCIS (Netherlands)

    HALBERTSMA, JPK; GOEKEN, LNH

    Passive muscle stretch tests are common practice in physical therapy and rehabilitation medicine. However, the effects of stretching exercises are not well known. With an instrumental straight-leg-raising set-up the extensibility, stiffness, and electromyographic activity of the hamstring muscles

  12. Tibialis anterior stretch reflex in early stance is suppressed by repetitive transcranial magnetic stimulation

    DEFF Research Database (Denmark)

    Zuur, Abraham T; Christensen, Mark Schram; Sinkjær, Thomas

    2009-01-01

    Abstract A rapid plantar flexion perturbation in the early stance phase of walking elicits a large stretch reflex in tibialis anterior (TA). In this study we use repetitive Transcranial Magnetic Stimulation (rTMS) to test if this response is mediated through a transcortical pathway. TA stretch...

  13. On prediction of OH stretching frequencies in intramolecularly hydrogen bonded systems

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Spanget-Larsen, Jens

    2012-01-01

    OH stretching frequencies are investigated for a series of non-tautomerizing systems with intramolecular hydrogen bonds. Effective OH stretching wavenumbers are predicted by the application of empirical correlation procedures based on the results of B3LYP/6-31G(d) theoretical calculations...

  14. The Acute Effects of Upper Extremity Stretching on Throwing Velocity in Baseball Throwers

    Directory of Open Access Journals (Sweden)

    Michael Williams

    2013-01-01

    Full Text Available Purpose. To examine the effects of static and proprioceptive neuromuscular facilitation (PNF stretching of the shoulder internal rotators on throwing velocity. Subjects. 27 male throwers (mean age = 25.1 years old, SD = 2.4 with adequate knowledge of demonstrable throwing mechanics. Study Design. Randomized crossover trial with repeated measures. Methods. Subjects warmed up, threw 10 pitches at their maximum velocity, were randomly assigned to 1 of 3 stretching protocols (static, PNF, or no stretch, and then repeated their 10 pitches. Velocities were recorded after each pitch and average and peak velocities were recorded after each session. Results. Data were analyzed using a repeated measures ANOVA. No significant interaction between stretching and throwing velocity was observed. Main effects for time were not statistically significant. Main effects for the stretching groups were statistically significant. Discussion. Results suggest that stretching of the shoulder internal rotators did not significantly affect throwing velocity immediately after stretching. This may be due to the complexity of the throwing task. Conclusions. Stretching may be included in a thrower's warm-up without any effects on throwing velocity. Further research should be performed using a population with more throwing experience and skill.

  15. The effects of static stretch duration on the flexibility of hamstring ...

    African Journals Online (AJOL)

    The effects of static stretch duration on the flexibility of hamstring muscles. NA Odunaiya, TK Hamzat, OF Ajayi. Abstract. The effects of duration of a static stretching protocol (Intervention) on hamstrings tightness were evaluated. Sixty purposively sampled subjects with unilateral hamstring tightness that had no history of low ...

  16. From Static Stretching to Dynamic Exercises: Changing the Warm-Up Paradigm

    Science.gov (United States)

    Young, Shawna

    2010-01-01

    In the United States, pre-exercise static stretching seems to have become common practice and routine. However, research suggests that it is time for a paradigm shift--that pre-exercise static stretching be replaced with dynamic warm-up exercises. Research indicates that a dynamic warm-up elevates body temperature, decreases muscle and joint…

  17. Muscular and stato-kinetic functions rehabilitation by means of subaquatic stretching (hydrostretching

    Directory of Open Access Journals (Sweden)

    Zoltàn Pàsztay

    2008-12-01

    Full Text Available Stretching is a physical therapeutical way for maintaining the standard parameters of the body functions from a tender to anadvanced age. The most important parameter that is influenced by the different techniques of stretching, especially byhydrostretching, is flexibility. This article presents the technique and the effects of hydrostretching on human body (onmuscular balance, strength, muscular metabolism and circulation.

  18. Acute effect of different stretching methods on flexibility and jumping performance in competitive artistic gymnasts.

    Science.gov (United States)

    Dallas, G; Smirniotou, A; Tsiganos, G; Tsopani, D; Di Cagno, A; Tsolakis, Ch

    2014-12-01

    The purpose of this study was to investigate the acute effects of 3 different warm up methods of stretching (static, proprioceptive neuromuscular facilitation, and stretching exercises on a Vibration platform) on flexibility and legs power-jumping performance in competitive artistic gymnasts. Eighteen competitive artistic gymnasts were recruited to participate in this study. Subjects were exposed to each of 3 experimental stretching conditions: static stretching (SS), proprioceptive neuromuscular facilitation stretching (PNF), and stretching exercises on a Vibration platform (S+V). Flexibility assessed with sit and reach test (S & R) and jumping performance with squat jump (SJ) and counter movement jump (CMJ) and were measured before, immediately after and 15 min after the interventions. Significant differences were observed for flexibility after all stretching conditions for S+V (+1.1%), SS (+5.7%) and PNF (+6.8%) (P=0.000), which remained higher 15 min after interventions (S+V (1.1%), SS (5.3%) and PNF (5.5%), respectively (P=0.000). PNF stretching increased flexibility in competitive gymnasts, while S+V maintained jumping performance when both methods were used as part of a warm-up procedure.

  19. Effect of Twisting and Stretching on Magneto Resistance and Spin Filtration in CNTs

    Directory of Open Access Journals (Sweden)

    Anil Kumar Singh

    2017-08-01

    Full Text Available Spin-dependent quantum transport properties in twisted carbon nanotube and stretched carbon nanotube are calculated using density functional theory (DFT and non-equilibrium green’s function (NEGF formulation. Twisting and stretching have no effect on spin transport in CNTs at low bias voltages. However, at high bias voltages the effects are significant. Stretching restricts any spin-up current in antiparallel configuration (APC, which results in higher magneto resistance (MR. Twisting allows spin-up current almost equivalent to the pristine CNT case, resulting in lower MR. High spin filtration is observed in PC and APC for pristine, stretched and twisted structures at all applied voltages. In APC, at low voltages spin filtration in stretched CNT is higher than in pristine and twisted ones, with pristine giving a higher spin filtration than twisted CNT.

  20. Post-activation depression of soleus stretch reflexes in healthy and spastic humans

    DEFF Research Database (Denmark)

    Grey, Michael James; Klinge, Klaus; Crone, Clarissa

    2007-01-01

    Reduced depression of transmitter release from Ia afferents following previous activation (post-activation depression) has been suggested to be involved in the pathophysiology of spasticity. However, the effect of this mechanism on the myotatic reflex and its possible contribution to increased...... reflex excitability in spastic participants has not been tested. To investigate these effects, we examined post-activation depression in Soleus H-reflex responses and in mechanically evoked Soleus stretch reflex responses. Stretch reflex responses were evoked with consecutive dorsiflexion perturbations...... of the soleus stretch reflex and H-reflex decreased as the interval between the stimulus/perturbation was decreased. Similarly, the stretch-evoked torque decreased. In the spastic participants, the post-activation depression of both reflexes and the stretch-evoked torque was significantly smaller than...

  1. Comparison between static stretching and the Pilates method on the flexibility of older women.

    Science.gov (United States)

    Oliveira, Laís Campos de; Oliveira, Raphael Gonçalves de; Pires-Oliveira, Deise Aparecida de Almeida

    2016-10-01

    Flexibility decreases with advancing age and some forms of exercise, such as static stretching and Pilates, can contribute to the improvement of this physical ability. To compare the effects of static stretching and Pilates on the flexibility of healthy older women, over the age of 60 years. Thirty-two volunteers were randomized into two groups (Static stretching or Pilates) to perform exercises for 60 min, twice a week, for three months. Evaluations to analyze the movements of the trunk (flexion and extension), hip flexion and plantar and dorsiflexion of the ankle were performed before and after the intervention, using a fleximeter. The static stretching exercises improved the trunk flexion and hip flexion movements, while the Pilates improved all evaluated movements. However, over time, the groups presented differences only for the trunk extension movement. For some body segments, Pilates may be more effective for improving flexibility in older women compared to static stretching. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Fatigue Crack Growth Characteristics of Cold Stretched STS 304 Welded Joint

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Won; Na, Seong Hyeon; Yoon, Dong Hyun; Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Kim, Young Kyun; Kim, Ki Dong [Korea Gas Coporation R& D Division, Daejeon (Korea, Republic of)

    2017-09-15

    STS 304 steel is used as pressure vessel material, and although it exhibits excellent mechanical characteristics at a low temperature, it is heavier than other materials. To address this issue, a method using cold-stretching techniques for STS 304 can be applied. In this study, a cold-stretching part and welded joint specimen were directly obtained from a cold-stretching pressure vessel manufactured according to ASME code. Fatigue crack propagation tests were carried out at room temperature and -170℃ using the compliance method for stress ratios of 0.1 and 0.5. The results indicate that crack growth rate of the welded joint is higher than that of the cold-stretching part within the same stress intensity factor range. The outcome of this work is expected to serve as a basis for the development of a cold-stretched STS 304 pressure vessel.

  3. Effectiveness of Manual Therapy and Stretching for Baseball Players With Shoulder Range of Motion Deficits.

    Science.gov (United States)

    Bailey, Lane B; Thigpen, Charles A; Hawkins, Richard J; Beattie, Paul F; Shanley, Ellen

    Baseball players displaying deficits in shoulder range of motion (ROM) are at increased risk of arm injury. Currently, there is a lack of consensus regarding the best available treatment options to restore shoulder ROM. Instrumented manual therapy with self-stretching will result in clinically significant deficit reductions when compared with self-stretching alone. Controlled laboratory study. Shoulder ROM and humeral torsion were assessed in 60 active baseball players (mean age, 19 ± 2 years) with ROM deficits (nondominant - dominant, ≥15°). Athletes were randomly assigned to receive a single treatment of instrumented manual therapy plus self-stretching (n = 30) or self-stretching only (n = 30). Deficits in internal rotation, horizontal adduction, and total arc of motion were compared between groups immediately before and after a single treatment session. Treatment effectiveness was determined by mean comparison data, and a number-needed-to-treat (NNT) analysis was used for assessing the presence of ROM risk factors. Prior to intervention, players displayed significant ( P < 0.001) dominant-sided deficits in internal rotation (-26°), total arc of motion (-18°), and horizontal adduction (-17°). After the intervention, both groups displayed significant improvements in ROM, with the instrumented manual therapy plus self-stretching group displaying greater increases in internal rotation (+5°, P = 0.010), total arc of motion (+6°, P = 0.010), and horizontal adduction (+7°, P = 0.004) compared with self-stretching alone. For horizontal adduction deficits, the added use of instrumented manual therapy with self-stretching decreased the NNT to 2.2 (95% CI, 2.1-2.4; P = 0.010). Instrumented manual therapy with self-stretching significantly reduces ROM risk factors in baseball players with motion deficits when compared with stretching alone. The added benefits of manual therapy may help to reduce ROM deficits in clinical scenarios where stretching alone is

  4. Quantifying stretching and rearrangement in epithelial sheet migration

    International Nuclear Information System (INIS)

    Lee, Rachel M; Nordstrom, Kerstin N; Losert, Wolfgang; Kelley, Douglas H; Ouellette, Nicholas T

    2013-01-01

    Although understanding the collective migration of cells, such as that seen in epithelial sheets, is essential for understanding diseases such as metastatic cancer, this motion is not yet as well characterized as individual cell migration. Here we adapt quantitative metrics used to characterize the flow and deformation of soft matter to contrast different types of motion within a migrating sheet of cells. Using a finite-time Lyapunov exponent (FTLE) analysis, we find that—in spite of large fluctuations—the flow field of an epithelial cell sheet is not chaotic. Stretching of a sheet of cells (i.e. positive FTLE) is localized at the leading edge of migration and increases when the cells are more highly stimulated. By decomposing the motion of the cells into affine and non-affine components using the metric D m in 2 , we quantify local plastic rearrangements and describe the motion of a group of cells in a novel way. We find an increase in plastic rearrangements with increasing cell densities, whereas inanimate systems tend to exhibit less non-affine rearrangements with increasing density. (paper)

  5. Finite Element Modeling of Reheat Stretch Blow Molding of PET

    Science.gov (United States)

    Krishnan, Dwarak; Dupaix, Rebecca B.

    2004-06-01

    Poly (ethylene terephthalate) or PET is a polymer used as a packaging material for consumer products such as beverages, food or other liquids, and in other applications including drawn fibers and stretched films. Key features that make it widely used are its transparency, dimensional stability, gas impermeability, impact resistance, and high stiffness and strength in certain preferential directions. These commercially useful properties arise from the fact that PET crystallizes upon deformation above the glass transition temperature. Additionally, this strain-induced crystallization causes the deformation behavior of PET to be highly sensitive to processing conditions. It is thus crucial for engineers to be able to predict its performance at various process temperatures, strain rates and strain states so as to optimize the manufacturing process. In addressing these issues; a finite element analysis of the reheat blow molding process with PET has been carried out using ABAQUS. The simulation employed a constitutive model for PET developed by Dupaix and Boyce et al.. The model includes the combined effects of molecular orientation and strain-induced crystallization on strain hardening when the material is deformed above the glass transition temperature. The simulated bottles were also compared with actual blow molded bottles to evaluate the validity of the simulation.

  6. Static stretch versus Mulligan Concept – long-term effects in gymnast’s flexibility

    Directory of Open Access Journals (Sweden)

    Manuela Karloh

    2010-04-01

    Full Text Available Flexibility is one of the most important physical aspects in Rhythmic Gymnastics (RG. The purpose of the study was to compare long-term changes in flexibility of hip extension in athletes of RG in function of two techniques: the static stretch and Mulligan’s Long Leg Traction. Participated eight female athletes with an average age of 13,25±0,89 years old, divided into two groups. Group 1 performed Mulligan technique and Group 2 performed static stretch. Flexibility training lasts for six weeks. It was executed 2 times a week, and was composed by 2 repetitions of 30 seconds for each lower limb. Photogrammetry was used to assess the range of motion (ROM of hip extension. ROM was assessed before and after six weeks of training. Descriptive and inferential statistics were used to analyze the data. The increase of ROM was statistically significant in both lower limbs in Group 1, and in right lower limb (RLL in Group 2. After six weeks of training the increase of ROM in Group 1 was 6,25°± 2,75º in left lower limb (LLL and 5,25°± 2,63º in RLL, and the increase in Group 2 was 6,75º± 4,64º in LLL and 5,5º± 3,41º in RLL. Comparing the two executed techniques, in relation to the increase of ROM, there were no statistically significant differences. We conclude that after six weeks of training the two proposed techniques have showed increases in range of motion.

  7. Structure and properties of highly oriented polyoxymethylene produced by hot stretching

    International Nuclear Information System (INIS)

    Zhao Xiaowen; Ye Lin

    2011-01-01

    Research highlights: → Highly oriented POM was fabricated through solid hot stretching technology → Tensile strength and modulus of POM increased remarkably with draw ratio. → The crystal structure of POM changed from spherulite to mat texture by drawing. → Crystallinity and orientation factor of POM increased remarkably by drawing. → The mechanical structure model of microfibril of POM was established. - Abstract: Highly oriented self-reinforced polyoxymethylene (POM) was successfully fabricated through solid phase hot stretching technology. The tensile strength and modulus increased with draw ratio, which reached 900 MPa and 12 GPa, respectively at a high draw ratio of 900% without remarkable drop of the elongation at break. The structure and morphology of the drawn products were studied and the mechanical structure model of microfibril of POM was established. Raman spectral exhibited a low-frequency shift, which indicated two types of molecular chains with different response to the stress. During drawing, the spherulitic structure of POM was broken up and the mat texture crystals were formed. With the increase of draw ratio, the melting peak moved to high temperature and an additional shoulder peak ascribed to melting of highly chain-extended and oriented crystalline blocks was observed. X-ray diffraction showed that the crystallinity and orientation factor increased, while the grain size perpendicular to (1 0 0) crystal plane of POM decreased by drawing. The α relaxation peak corresponding to the glass transition temperature of POM (T g ) moved to high temperature with draw ratio. The section morphology of drawn POM exhibited a fibrillar structure which contributed to the significantly high tensile strength and modulus of the product.

  8. Ex vivo stretch reveals altered mechanical properties of isolated dystrophin-deficient hearts.

    Directory of Open Access Journals (Sweden)

    Matthew S Barnabei

    Full Text Available Duchenne muscular dystrophy (DMD is a progressive and fatal disease of muscle wasting caused by loss of the cytoskeletal protein dystrophin. In the heart, DMD results in progressive cardiomyopathy and dilation of the left ventricle through mechanisms that are not fully understood. Previous reports have shown that loss of dystrophin causes sarcolemmal instability and reduced mechanical compliance of isolated cardiac myocytes. To expand upon these findings, here we have subjected the left ventricles of dystrophin-deficient mdx hearts to mechanical stretch. Unexpectedly, isolated mdx hearts showed increased left ventricular (LV compliance compared to controls during stretch as LV volume was increased above normal end diastolic volume. During LV chamber distention, sarcomere lengths increased similarly in mdx and WT hearts despite greater excursions in volume of mdx hearts. This suggests that the mechanical properties of the intact heart cannot be modeled as a simple extrapolation of findings in single cardiac myocytes. To explain these findings, a model is proposed in which disruption of the dystrophin-glycoprotein complex perturbs cell-extracellular matrix contacts and promotes the apparent slippage of myocytes past each other during LV distension. In comparison, similar increases in LV compliance were obtained in isolated hearts from β-sarcoglycan-null and laminin-α(2 mutant mice, but not in dysferlin-null mice, suggesting that increased whole-organ compliance in mdx mice is a specific effect of disrupted cell-extracellular matrix contacts and not a general consequence of cardiomyopathy via membrane defect processes. Collectively, these findings suggest a novel and cell-death independent mechanism for the progressive pathological LV dilation that occurs in DMD.

  9. Utilizing stretch-tunable thermochromic elastomeric opal films as novel reversible switchable photonic materials.

    Science.gov (United States)

    Schäfer, Christian G; Lederle, Christina; Zentel, Kristina; Stühn, Bernd; Gallei, Markus

    2014-11-01

    In this work, the preparation of highly thermoresponsive and fully reversible stretch-tunable elastomeric opal films featuring switchable structural colors is reported. Novel particle architectures based on poly(diethylene glycol methylether methacrylate-co-ethyl acrylate) (PDEGMEMA-co-PEA) as shell polymer are synthesized via seeded and stepwise emulsion polymerization protocols. The use of DEGMEMA as comonomer and herein established synthetic strategies leads to monodisperse soft shell particles, which can be directly processed to opal films by using the feasible melt-shear organization technique. Subsequent UV crosslinking strategies open access to mechanically stable and homogeneous elastomeric opal films. The structural colors of the opal films feature mechano- and thermoresponsiveness, which is found to be fully reversible. Optical characterization shows that the combination of both stimuli provokes a photonic bandgap shift of more than 50 nm from 560 nm in the stretched state to 611 nm in the fully swollen state. In addition, versatile colorful patterns onto the colloidal crystal structure are produced by spatial UV-induced crosslinking by using a photomask. This facile approach enables the generation of spatially cross-linked switchable opal films with fascinating optical properties. Herein described strategies for the preparation of PDEGMEMA-containing colloidal architectures, application of the melt-shear ordering technique, and patterned crosslinking of the final opal films open access to novel stimuli-responsive colloidal crystal films, which are expected to be promising materials in the field of security and sensing applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Thermo-mechanical simulation of liquid-supported stretch blow molding

    International Nuclear Information System (INIS)

    Zimmer, J.; Stommel, M.

    2015-01-01

    Stretch blow molding is the well-established plastics forming method to produce Polyehtylene therephtalate (PET) bottles. An injection molded preform is heated up above the PET glass transition temperature (Tg∼85°C) and subsequently inflated by pressurized air into a closed cavity. In the follow-up filling process, the resulting bottle is filled with the final product. A recently developed modification of the process combines the blowing and filling stages by directly using the final liquid product to inflate the preform. In a previously published paper, a mechanical simulation and successful evaluation of this liquid-driven stretch blow molding process was presented. In this way, a realistic process parameter dependent simulation of the preform deformation throughout the forming process was enabled, whereas the preform temperature evolution during forming was neglected. However, the formability of the preform is highly reduced when the temperature sinks below Tg during forming. Experimental investigations show temperature-induced failure cases due to the fast heat transfer between hot preform and cold liquid. Therefore, in this paper, a process dependent simulation of the temperature evolution during processing to avoid preform failure is presented. For this purpose, the previously developed mechanical model is used to extract the time dependent thickness evolution. This information serves as input for the heat transfer simulation. The required material parameters are calibrated from preform cooling experiments recorded with an infrared-camera. Furthermore, the high deformation ratios during processing lead to strain induced crystallization. This exothermal reaction is included into the simulation by extracting data from preform measurements at different stages of deformation via Differential Scanning Calorimetry (DSC). Finally, the thermal simulation model is evaluated by free forming experiments, recorded by a high-speed infrared camera

  11. Chiropractic manipulative therapy of the thoracic spine in combination with stretch and strengthening exercises, in improving postural kyphosis in woman

    Directory of Open Access Journals (Sweden)

    Kim C. Branco

    2016-10-01

    Method: A randomised study design with thirty female participants between the ages of twenty and  thirty nine was selected. Group 1 (n = 10 received chiropractic spinal manipulative therapy to the thoracic spine. Group 2 (n = 10 received chiropractic spinal manipulative therapy to the thoracic spine as well as stretch and strengthening exercises i.e. stretching the pectoralis major muscles and strengthening the rhomboid, middle and inferior trapezius muscles. Group 3 (n = 10 received stretch and strengthening exercises. The stretch and strengthening exercises were performed in the consultation rooms to ensure that the participants were complying with the treatment and doing the exercises properly. The study consisted of seven consultations for Group 1 (they received treatment once a week for six weeks and for Groups 2 and 3 there were nineteen consultations (they received three treatments a week for six weeks. Objective data was recorded at the beginning of the first, fourth and seventh consultations for Group 1, and the first, tenth and nineteenth consultations for Groups 2 and 3. On the seventh consultation (for Group 1 and nineteenth consultation for Groups 2 and 3, only data collection was done. Objective data were obtained by using the Flexicurve® Ruler measurements for the angle of kyphosis. Visual analysis was done by taking lateral (sagittal view photographs at the beginning of the initial and final consultations. Results: Statistical analysis revealed significant statistical changes for the intragroup results for all three groups. No significant statistical difference was found between the groups for the inter-group analysis. Conclusion: The study showed that all three treatment protocols for Groups 1, 2, and 3 were effective. However, Group 1 had not shown a great improvement in their postural kyphosis, Group 3 had shown a relatively good improvement in their posture, while Group 2 had shown the best results with regards to improvement of the

  12. A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

    KAUST Repository

    Chang, Y.-H.; Chen, S.-C.; Wang, T.-J.; Guo, J.

    2018-01-01

    Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non

  13. Image-based multiscale mechanical modeling shows the importance of structural heterogeneity in the human lumbar facet capsular ligament.

    Science.gov (United States)

    Zarei, Vahhab; Liu, Chao J; Claeson, Amy A; Akkin, Taner; Barocas, Victor H

    2017-08-01

    The lumbar facet capsular ligament (FCL) primarily consists of aligned type I collagen fibers that are mainly oriented across the joint. The aim of this study was to characterize and incorporate in-plane local fiber structure into a multiscale finite element model to predict the mechanical response of the FCL during in vitro mechanical tests, accounting for the heterogeneity in different scales. Characterization was accomplished by using entire-domain polarization-sensitive optical coherence tomography to measure the fiber structure of cadaveric lumbar FCLs ([Formula: see text]). Our imaging results showed that fibers in the lumbar FCL have a highly heterogeneous distribution and are neither isotropic nor completely aligned. The averaged fiber orientation was [Formula: see text] ([Formula: see text] in the inferior region and [Formula: see text] in the middle and superior regions), with respect to lateral-medial direction (superior-medial to inferior-lateral). These imaging data were used to construct heterogeneous structural models, which were then used to predict experimental gross force-strain behavior and the strain distribution during equibiaxial and strip biaxial tests. For equibiaxial loading, the structural model fit the experimental data well but underestimated the lateral-medial forces by [Formula: see text]16% on average. We also observed pronounced heterogeneity in the strain field, with stretch ratios for different elements along the lateral-medial axis of sample typically ranging from about 0.95 to 1.25 during a 12% strip biaxial stretch in the lateral-medial direction. This work highlights the multiscale structural and mechanical heterogeneity of the lumbar FCL, which is significant both in terms of injury prediction and microstructural constituents' (e.g., neurons) behavior.

  14. The influence of foot position on stretching of the plantar fascia.

    Science.gov (United States)

    Flanigan, Ryan M; Nawoczenski, Deborah A; Chen, Linlin; Wu, Hulin; DiGiovanni, Benedict F

    2007-07-01

    A recent study found nonweightbearing stretching exercises specific to the plantar fascia to be superior to the standard program of weightbearing Achilles tendon-stretching exercises in patients with chronic plantar fasciitis. The present study used a cadaver model to demonstrate the influence of foot and ankle position on stretching of the plantar fascia. Twelve fresh-frozen lower-leg specimens were tested in 15 different configurations representing various combinations of ankle and metatarsophalangeal (MTP) joint dorsiflexion, midtarsal transverse plane abduction and adduction, and forefoot varus and valgus. Measurements were recorded by a differential variable reluctance transducer (DVRT) implanted into the medial band of the plantar fascia, and primary measurement was a percent deformation of the plantar fascia (stretch) with respect to a reference position (90 degrees ankle dorsiflexion, 0 degrees midtarsal and forefoot orientation, and 0 degrees MTP dorsiflexion). Ankle and MTP joint dorsiflexion produced a significant increase (14.91%) in stretch compared to the position of either ankle dorsiflexion alone (9.31% increase, p plantar fascia tissue-specific stretching exercises and lends support to the use of ankle and MTP joint dorsiflexion when employing stretching protocols for nonoperative treatment in patients with chronic proximal plantar fasciitis.

  15. Mechanical stretching stimulates collagen synthesis via down-regulating SO2/AAT1 pathway

    Science.gov (United States)

    Liu, Jia; Yu, Wen; Liu, Yan; Chen, Selena; Huang, Yaqian; Li, Xiaohui; Liu, Cuiping; Zhang, Yanqiu; Li, Zhenzhen; Du, Jie; Tang, Chaoshu; Du, Junbao; Jin, Hongfang

    2016-01-01

    The aim of the study was to investigate the role of endogenous sulfur dioxide (SO2)/ aspartate aminotransferase 1 (AAT1) pathway in stretch-induced excessive collagen expression and its mechanism. The mechanical stretch downregulated SO2/AAT1 pathway and increased collagen I and III protein expression. Importantly, AAT1 overexpression blocked the increase in collagen I and III expression, transforming growth factor-β1 (TGF- β1) expression and phosphorylation of Smad2/3 induced by stretch, but AAT1 knockdown mimicked the increase in collagen I and III expression, TGF- β1 expression and phosphorylation of Smad2/3 induced by stretch. Mechanistically, SB431542, a TGF-β1/Smad2/3 inhibitor, eliminated excessive collagen I and III accumulation induced by AAT1 knockdown, stretch or stretch plus AAT1 knockdown. In a rat model of high pulmonary blood flow-induced pulmonary vascular collagen accumulation, AAT1 expression and SO2 content in lung tissues of rat were reduced in shunt rats with high pulmonary blood flow. Supplement of SO2 derivatives inhibited activation of TGF- β1/Smad2/3 pathway and alleviated the excessive collagen accumulation in lung tissues of shunt rats. The results suggested that deficiency of endogenous SO2/AAT1 pathway mediated mechanical stretch-stimulated abnormal collagen accumulation via TGF-β1/Smad2/3 pathway. PMID:26880260

  16. A study of extracellular matrix remodeling in aortic heart valves using a novel biaxial stretch bioreactor.

    Science.gov (United States)

    Lei, Ying; Masjedi, Shirin; Ferdous, Zannatul

    2017-11-01

    In aortic valves, biaxial cyclic stretch is known to modulate cell differentiation, extracellular matrix (ECM) synthesis and organization. We designed a novel bioreactor that can apply independent and precise stretch along radial and circumferential directions in a tissue culture environment. While this bioreactor can be used for either native or engineered tissues, this study determined matrix remodeling and strain distribution of aortic cusps after culturing under biaxial stretch for 14 days. The contents of collagen and glycosaminoglycans were determined using standard biochemical assays and compared with fresh controls. Strain fields in static cusps were more uniform than those in stretched cusps, which indicated degradation of the ECM fibers. The glycosaminoglycan content was significantly elevated in the static control as compared to fresh or stretched cusps, but no difference was observed in collagen content among the groups. The strain profile of freshly isolated fibrosa vs. ventricularis and left, right, and noncoronary cusps were also determined by Digital Image Correlation technique. Distinct strain patterns were observed under stretch on fibrosa and ventricularis sides and among the three cusps. This work highlights the critical role of the anisotropic ECM structure for proper functions of native aortic valves and the beneficial effects of biaxial stretch for maintenance of the native ECM structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Periostin inhibits mechanical stretch-induced apoptosis in osteoblast-like MG-63 cells.

    Science.gov (United States)

    Yu, Kai-Wen; Yao, Chung-Chen; Jeng, Jiiang-Huei; Shieh, Hao-Ying; Chen, Yi-Jane

    2018-04-01

    Appropriate mechanical stress plays an important role in regulating the proliferation and differentiation of osteoblasts, whereas high-level mechanical stress may be harmful and compromise cell survival. Periostin, a matricellular protein, is essential in maintaining functional integrity of bone and collagen-rich connective tissue in response to mechanical stress. This study investigated whether or not high-level mechanical stretch induces cell apoptosis and the regulatory role of periostin in mechanical stretch-induced apoptosis in osteoblastic cells. Osteoblast-like MG-63 cells were seeded onto Bio-Flex I culture plates and subjected to cyclic mechanical stretching (15% elongation, 0.1 Hz) in a Flexercell tension plus system-5000. The same process was applied to cells pre-treated with exogenous human recombinant periostin before mechanical stretching. We used a chromatin condensation and membrane permeability dead cell apoptosis kit to evaluate the stretch-induced cell responses. Expression of caspase-3 and cPARP was examined by immunofluorescent stain and flow cytometry. The expression of periostin in MG-63 cells is involved in the TGF-β signaling pathway. High-level cyclic mechanical stretch induced apoptotic responses in MG-63 osteoblastic cells. The percentages of apoptotic cells and cells expressing cPARP protein increased in the groups of cells subjected to mechanical stretch, but these responses were absent in the presence of exogenous periostin. Our study revealed that high-level mechanical stretch induces apoptotic cell death, and that periostin plays a protective role against mechanical stretch-induced apoptosis in osteoblastic cells. Copyright © 2017. Published by Elsevier B.V.

  18. Upper Limb Static-Stretching Protocol Decreases Maximal Concentric Jump Performance

    Directory of Open Access Journals (Sweden)

    Paulo H. Marchetti

    2014-12-01

    Full Text Available The purpose of the present study was to evaluate the acute effects of an upper limb static-stretching (SS protocol on the maximal concentric jump performance. We recruited 25 young healthy, male, resistance trained individuals (stretched group, n = 15 and control group, n = 10 in this study. The randomized between group experimental protocol consisted of a three trials of maximal concentric jump task, before and after a SS of the upper limb. Vertical ground reaction forces (vGRF and surface electromyography (sEMG of both gastrocnemius lateralis (GL and vastus lateralis (VL were acquired. An extensive SS was employed consisting of ten stretches of 30 seconds, with 15 seconds of rest, and 70-90% of the point of discomfort (POD. ANOVA (2x2 (group x condition was used for shoulder joint range of motion (ROM, vGRF and sEMG. A significant interaction for passive ROM of the shoulder joint revealed significant increases between pre- and post-SS protocol (p < 0.001. A significant interaction demonstrated decreased peak force and an increased peak propulsion duration between pre- and post-stretching only for stretch group (p = 0.021, and p = 0.024, respectively. There was a significant main effect between groups (stretch and control for peak force for control group (p = 0.045. Regarding sEMG variables, there were no significant differences between groups (control versus stretched or condition (pre-stretching versus post-stretching for the peak amplitude of RMS and IEMG for both muscles (VL and GL. In conclusion, an acute extensive SS can increase the shoulder ROM, and negatively affect both the propulsion duration and peak force of the maximal concentric jump, without providing significant changes in muscle activation.

  19. Graphical analysis for gel morphology II. New mathematical approach for stretched exponential function with β>1

    Science.gov (United States)

    Hashimoto, Chihiro; Panizza, Pascal; Rouch, Jacques; Ushiki, Hideharu

    2005-10-01

    A new analytical concept is applied to the kinetics of the shrinking process of poly(N-isopropylacrylamide) (PNIPA) gels. When PNIPA gels are put into hot water above the critical temperature, two-step shrinking is observed and the secondary shrinking of gels is fitted well by a stretched exponential function. The exponent β characterizing the stretched exponential is always higher than one, although there are few analytical concepts for the stretched exponential function with β>1. As a new interpretation for this function, we propose a superposition of step (Heaviside) function and a new distribution function of characteristic time is deduced.

  20. Graphical analysis for gel morphology II. New mathematical approach for stretched exponential function with β>1

    International Nuclear Information System (INIS)

    Hashimoto, Chihiro; Panizza, Pascal; Rouch, Jacques; Ushiki, Hideharu

    2005-01-01

    A new analytical concept is applied to the kinetics of the shrinking process of poly(N-isopropylacrylamide) (PNIPA) gels. When PNIPA gels are put into hot water above the critical temperature, two-step shrinking is observed and the secondary shrinking of gels is fitted well by a stretched exponential function. The exponent β characterizing the stretched exponential is always higher than one, although there are few analytical concepts for the stretched exponential function with β>1. As a new interpretation for this function, we propose a superposition of step (Heaviside) function and a new distribution function of characteristic time is deduced

  1. Graphical analysis for gel morphology II. New mathematical approach for stretched exponential function with {beta}>1

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Chihiro [Graduate School of Bio-Application and System Engineering (BASE), Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi Tokyo 185-0054 (Japan); Panizza, Pascal [Centre de Physique Moleculaire Optique et Hertzienne (CPMOH), Bordeaux I University, 351 Cours de la Liberation 33405 Talance (France); Rouch, Jacques [Centre de Physique Moleculaire Optique et Hertzienne (CPMOH), Bordeaux I University, 351 Cours de la Liberation 33405 Talance (France); Ushiki, Hideharu [Graduate School of Bio-Application and System Engineering (BASE), Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi Tokyo 185-0054 (Japan)

    2005-10-19

    A new analytical concept is applied to the kinetics of the shrinking process of poly(N-isopropylacrylamide) (PNIPA) gels. When PNIPA gels are put into hot water above the critical temperature, two-step shrinking is observed and the secondary shrinking of gels is fitted well by a stretched exponential function. The exponent {beta} characterizing the stretched exponential is always higher than one, although there are few analytical concepts for the stretched exponential function with {beta}>1. As a new interpretation for this function, we propose a superposition of step (Heaviside) function and a new distribution function of characteristic time is deduced.

  2. Adaptation of the dermal collagen structure of human skin and scar tissue in response to stretch: An experimental study

    NARCIS (Netherlands)

    Verhaegen, Pauline D.; Schouten, Hennie J.; Tigchelaar-Gutter, Wikky; van Marle, Jan; van Noorden, Cornelis J.; Middelkoop, Esther; van Zuijlen, Paul P.

    2012-01-01

    Surgeons are often faced with large defects that are difficult to close. Stretching adjacent skin can facilitate wound closure. In clinical practice, intraoperative stretching is performed in a cyclical or continuous fashion. However, exact mechanisms of tissue adaptation to stretch remain unclear.

  3. Evaluation of retail fresh meat packagings covered with stretch films of plasticized PVC and non-PVC alternatives

    DEFF Research Database (Denmark)

    Petersen, Jens Højslev; Togeskov, P.; Hallas, J.

    2004-01-01

    The characteristics and performance of several non-PVC stretch films were compared to those of plasticized PVC. Initially the main polymer components Of the film were identified by infrared spectrometry and differential scanning calorimetry. The differences between films in mechanical properties......, such as puncture resistance and tensile strength, varied about a factor of two, while the differences in elongation at break were considerably higher. Plasticized PVC showed properties somewhere in the middle. The water vapour transmission was highest for PVC, while its permeability to oxygen was the lowest...

  4. Chiropractic manipulative therapy of the thoracic spine in combination with stretch and strengthening exercises, in improving postural kyphosis in woman

    Directory of Open Access Journals (Sweden)

    Kim Castello Branco

    2016-12-01

    Conclusion: The study showed that all three treatment protocols for Groups 1, 2, and 3 were effective. However, Group 1 had not shown a great improvement in their postural kyphosis, Group 3 had shown a relatively good improvement in their posture, while Group 2 had shown the best results with regards to improvement of the participants' posture. Therefore, in conclusion, Groups 2 and 3 treatment protocols can be used effectively to treat postural kyphosis but Group 2's treatment protocol, consisting of chiropractic spinal manipulative therapy to the thoracic spine in combination with stretch and strengthening exercises, will yield the best results.

  5. Effect of spinal manipulative therapy with stretching compared with stretching alone on full-swing performance of golf players: a randomized pilot trial☆

    Science.gov (United States)

    Costa, Soraya M.V.; Chibana, Yumi E.T.; Giavarotti, Leandro; Compagnoni, Débora S.; Shiono, Adriana H.; Satie, Janice; Bracher, Eduardo S.B.

    2009-01-01

    Abstract Objective There has been a steady growth of chiropractic treatment using spinal manipulative therapy (SMT) that aims to increase the performance of athletes in various sports. This study evaluates the effect of SMT by chiropractors on the performance of golf players. Methods Golfers of 2 golf clubs in São Paulo, Brazil, participated in this study. They were randomized to 1 of 2 groups: Group I received a stretch program, and group II received a stretch program in addition to SMT. Participants in both groups performed the same standardized stretching program. Spinal manipulative therapy to dysfunctional spinal segments was performed on group II only. All golfers performed 3 full-swing maneuvers. Ball range was considered as the average distance for the 3 shots. Treatment was performed after the initial measurement, and the same maneuvers were performed afterward. Each participant repeated these procedures for a 4-week period. Student t test, Mann-Whitney nonparametric test, and 1-way analysis of variance for repeated measures with significance level of 5% were used to analyze the study. Results Forty-three golfers completed the protocol. Twenty participants were allocated to group I and 23 to group II. Average age, handicap, and initial swing were comparable. No improvement of full-swing performance was observed during the 4 sessions on group I (stretch only). An improvement was observed at the fourth session of group II (P = .005); when comparing the posttreatment, group II had statistical significance at all phases (P = .003). Conclusions Chiropractic SMT in association with muscle stretching may be associated with an improvement of full-swing performance when compared with muscle stretching alone. PMID:19948307

  6. Unsteady Magnetized Flow and Heat Transfer of a Viscoelastic fluid over a Stretching Surface

    Science.gov (United States)

    Ghosh, Sushil Kumar

    2017-12-01

    This paper is to study the flow of heated ferro-fluid over a stretching sheet under the influence of magnetic field. The fluid considered in the present investigation is a mixture of blood as well as fluid-dispersed magnetic nano particles and under this context blood is found to be the appropriate choice of viscoelastic, Walter's B fluid. The objective of the present work is to study the effect of various parameters found in the mathematical analysis. Taking into account the blood has zero electrical conductivity, magnetization effect has been considered in the governing equation of the present study with the use of ferro-fluid dynamics principle. By introducing appropriate non-dimensional variables into the governing equations of unsteady two-dimensional flow of viscoelastic fluid with heat transfer are converted to a set of ordinary differential equations with appropriate boundary conditions. Newton's linearization technique has been employed for the solution of non-linear ordinary differential equations. Important results found in the present investigation are the substantial influence of ferro-magnetic parameter, Prandlt number and the parameter associated with the thermal conductivity on the flow and heat transfer. It is observed that the presence of magnetic dipole essentially reduces the flow velocity in the vertical direction and that helps to damage the cancer cells in the tumor region.

  7. Fibre Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    CERN Document Server

    Benussi, Luigi

    2015-01-01

    Fibre Bragg Grating (FBG) sensors have been so far mainly used in high energy physics as high precision positioning and re-positioning sensor and as low cost, easy to mount and low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS upgrade consists of 144 GEM chambers of about 0.5 $m^{2}$ active area each and based on the triple GEMs technology, to be installed in the very forward region of the CMS endcap. The large active are of each GE1/1 chamber consists of a single GEM foil (the GE1/1 chambers represent the largest GEM foils assembled and operated so far) to be mechanically stretched in order to secure its flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. A network of FBG sensors have been used to determine the optimal m...

  8. Effects of aerobic training combined with respiratory muscle stretching on the functional exercise capacity and thoracoabdominal kinematics in patients with COPD: a randomized and controlled trial

    Directory of Open Access Journals (Sweden)

    Wada JT

    2016-10-01

    Full Text Available Juliano T Wada,1 Erickson Borges-Santos,1 Desiderio Cano Porras,1 Denise M Paisani,1 Alberto Cukier,2 Adriana C Lunardi,1 Celso RF Carvalho1 1Department of Physical Therapy, 2Department of Cardiopneumology, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil Background: Patients with COPD present a major recruitment of the inspiratory muscles, predisposing to chest incoordination, increasing the degree of dyspnea and impairing their exercise capacity. Stretching techniques could decrease the respiratory muscle activity and improve their contractile capacity; however, the systemic effects of stretching remain unknown.Objective: The aim of this study was to evaluate the effects of aerobic training combined with respiratory muscle stretching on functional exercise capacity and thoracoabdominal kinematics in patients with COPD.Design: This study was a randomized and controlled trial.Participants: A total of 30 patients were allocated to a treatment group (TG or a control group (CG; n=15, each group.Intervention: The TG was engaged in respiratory muscle stretching and the CG in upper and lower limb muscle stretching. Both groups performed 24 sessions (twice a week, 12 weeks of aerobic training.Evaluations: Functional exercise capacity (6-minute walk test, thoracoabdominal kinematics (optoelectronic plethysmography, and respiratory muscle activity (surface electromyography were evaluated during exercise. Analysis of covariance was used to compare the groups at a significance level of 5%.Results: After the intervention, the TG showed improved abdominal (ABD contribution, compartmental volume, mobility, and functional exercise capacity with decreased dyspnea when compared with the CG (P<0.01. The TG also showed a decreased respiratory muscle effort required to obtain the same pulmonary volume compared to the CG (P<0.001.Conclusion: Our results suggest that aerobic training combined with respiratory muscle stretching increases the functional

  9. Low-timing-jitter, stretched-pulse passively mode-locked fiber laser with tunable repetition rate and high operation stability

    International Nuclear Information System (INIS)

    Liu, Yuanshan; Zhang, Jian-Guo; Chen, Guofu; Zhao, Wei; Bai, Jing

    2010-01-01

    We design a low-timing-jitter, repetition-rate-tunable, stretched-pulse passively mode-locked fiber laser by using a nonlinear amplifying loop mirror (NALM), a semiconductor saturable absorber mirror (SESAM), and a tunable optical delay line in the laser configuration. Low-timing-jitter optical pulses are stably produced when a SESAM and a 0.16 m dispersion compensation fiber are employed in the laser cavity. By inserting a tunable optical delay line between NALM and SESAM, the variable repetition-rate operation of a self-starting, passively mode-locked fiber laser is successfully demonstrated over a range from 49.65 to 50.47 MHz. The experimental results show that the newly designed fiber laser can maintain the mode locking at the pumping power of 160 mW to stably generate periodic optical pulses with width less than 170 fs and timing jitter lower than 75 fs in the 1.55 µm wavelength region, when the fundamental repetition rate of the laser is continuously tuned between 49.65 and 50.47 MHz. Moreover, this fiber laser has a feature of turn-key operation with high repeatability of its fundamental repetition rate in practice

  10. Fatigue and muscle-tendon stiffness after stretch-shortening cycle and isometric exercise.

    Science.gov (United States)

    Toumi, Hechmi; Poumarat, Georges; Best, Thomas M; Martin, Alain; Fairclough, John; Benjamin, Mike

    2006-10-01

    The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch-shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90 degrees of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle-tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.

  11. Surface dose measurements under stretched, perforated thermoplast sheets and under protective wound dressings for high energy photon radiation

    International Nuclear Information System (INIS)

    Staudenraus, J.; Christ, G.

    2000-01-01

    Patient fixation masks made of perforated thermoplast sheets are widely used in radiotherapy. These masks in particular serve to immobilize the head and neck region during radiation treatment. We placed samples made of differently stretched, perforated mask material on the surface of a white polystyrene (RW3) phantom and measured for high energy photon beams from Co-60 radiation up to 25 MV bremsstrahlung the dose increase resulting from the build-up under the hole and bridge areas. Depending on the energy of the incident beam and the thickness of the stretched mask material we observed a dose increase under the bridges at the phantom surface of 55% up to 140% compared to the dose without a layer of mask material. Under a hole the dose increase is almost half the value found under a bridge. However, deeper than 1 mm under the phantom surface this difference in dose increase under holes and bridges decreases to less than 10%. The mean dose increase under a perforated thermoplast sheet is lower than the dose increase under a homogeneous sheet made of the same material with the same mean thickness. Radiation induced skin lesions or an ulcerating tumour, respectively, may require a protective wound dressing under a patient fixation mask during radiation therapy. Choosing a thin hydrocolloid wound dressing the additional dose increase of the skin, compared to the dose increase due to the fixation mask, can be kept low. (orig.) [de

  12. Explicit Gaussian quadrature rules for C^1 cubic splines with symmetrically stretched knot sequence

    KAUST Repository

    Ait-Haddou, Rachid; Barton, Michael; Calo, Victor M.

    2015-01-01

    We provide explicit expressions for quadrature rules on the space of C^1 cubic splines with non-uniform, symmetrically stretched knot sequences. The quadrature nodes and weights are derived via an explicit recursion that avoids an intervention

  13. THUNDER Piezoelectric Actuators as a Method of Stretch-Tuning an Optical Fiber Grating

    Science.gov (United States)

    Allison, Sidney G.; Fox, Robert L.; Froggatt, Mark E.; Childers, Brooks A.

    2000-01-01

    A method of stretching optical fiber holds interest for measuring strain in smart structures where the physical displacement may be used to tune optical fiber lasers. A small, light weight, low power tunable fiber laser is ideal for demodulating strain in optical fiber Bragg gratings attached to smart structures such as the re-usable launch vehicle that is being developed by NASA. A method is presented for stretching optical fibers using the THUNDER piezoelectric actuators invented at NASA Langley Research Center. THUNDER actuators use a piezoelectric layer bonded to a metal backing to enable the actuators to produce displacements larger than the unbonded piezoelectric material. The shift in reflected optical wavelength resulting from stretching the fiber Bragg grating is presented. Means of adapting THUNDER actuators for stretching optical fibers is discussed, including ferrules, ferrule clamp blocks, and plastic hinges made with stereo lithography.

  14. Coherent time-stretch transformation for real-time capture of wideband signals.

    Science.gov (United States)

    Buckley, Brandon W; Madni, Asad M; Jalali, Bahram

    2013-09-09

    Time stretch transformation of wideband waveforms boosts the performance of analog-to-digital converters and digital signal processors by slowing down analog electrical signals before digitization. The transform is based on dispersive Fourier transformation implemented in the optical domain. A coherent receiver would be ideal for capturing the time-stretched optical signal. Coherent receivers offer improved sensitivity, allow for digital cancellation of dispersion-induced impairments and optical nonlinearities, and enable decoding of phase-modulated optical data formats. Because time-stretch uses a chirped broadband (>1 THz) optical carrier, a new coherent detection technique is required. In this paper, we introduce and demonstrate coherent time stretch transformation; a technique that combines dispersive Fourier transform with optically broadband coherent detection.

  15. Influence of acute static stretching on the behavior of maximum muscle strength

    Directory of Open Access Journals (Sweden)

    Carmen Lúcia Borges Bastos

    2014-06-01

    Full Text Available The aim of this study was to compare the influence of acute static stretching on maximal muscle strength (1RM. The non-probabilistic sample consisted of 30 subjects split into two groups: static stretching (SS= 15 and without stretching group (WS= 15. Muscle strength evaluation (1RM was conducted with a Dynamometer model 32527pp400 Pound push / pull devices coupled in knee extension (KE and bench press (BP. The Wilcoxon test for intragroup comparisons and the Kruskal-Wallis test for comparisons between groups (p< 0.05 were selected. There were no significant differences (p> 0.05 between the SS and WS in exercise KE and BP. Therefore, it can be concluded that there was no reduction in the performance of 1RM performing the exercises KE and BP when preceded by static stretching.

  16. Study of the solvent effects on the molecular structure and Cdbnd O stretching vibrations of flurbiprofen

    Science.gov (United States)

    Tekin, Nalan; Pir, Hacer; Sagdinc, Seda

    2012-12-01

    The effects of 15 solvents on the C=O stretching vibrational frequency of flurbiprofen (FBF) were determined to investigate solvent-solute interactions. Solvent effects on the geometry and C=O stretching vibrational frequency, ν(C=O), of FBF were studied theoretically at the DFT/B3LYP and HF level in combination with the polarizable continuum model and experimentally using attenuated total reflection infrared spectroscopy (ATR-IR). The calculated C=O stretching frequencies in the liquid phase are in agreement with experimental values. Moreover, the wavenumbers of ν(C=O) of FBF in different solvents have been obtained and correlated with the Kirkwood-Bauer-Magat equation (KBM), the solvent acceptor numbers (ANs), and the linear solvation energy relationships (LSERs). The solvent-induced stretching vibrational frequency shifts displayed a better correlation with the LSERs than with the ANs and KBM.

  17. A supervision on stretch out mode of Guangdong Daya Bay NPP

    International Nuclear Information System (INIS)

    Zhou Hong; Chai Guohan; Dong Xiuchen; Mao Haiyun

    2004-01-01

    The supervision of stretch out mode in the Guangdong Daya Bay nuclear power plant is described. It is also discussed some problems and suggestions of supervision in the new fields of the nuclear power plan. (authors)

  18. Intrinsic ankle stiffness during standing increases with ankle torque and passive stretch of the Achilles tendon

    Science.gov (United States)

    Gill, Jaspret

    2018-01-01

    Individuals may stand with a range of ankle angles. Furthermore, shoes or floor surfaces may elevate or depress their heels. Here we ask how these situations impact ankle stiffness and balance. We performed two studies (each with 10 participants) in which the triceps surae, Achilles tendon and aponeurosis were stretched either passively, by rotating the support surface, or actively by leaning forward. Participants stood freely on footplates which could rotate around the ankle joint axis. Brief, small stiffness-measuring perturbations (torque or passive stretch. Sway was minimally affected by stretch or lean, suggesting that this did not underlie the alterations in stiffness. In quiet stance, maximum ankle stiffness is limited by the tendon. As tendon strain increases, it becomes stiffer, causing an increase in overall ankle stiffness, which would explain the effects of leaning. However, stiffness also increased considerably with passive stretch, despite a modest torque increase. We discuss possible explanations for this increase. PMID:29558469

  19. Reducing charging effects in scanning electron microscope images by Rayleigh contrast stretching method (RCS).

    Science.gov (United States)

    Wan Ismail, W Z; Sim, K S; Tso, C P; Ting, H Y

    2011-01-01

    To reduce undesirable charging effects in scanning electron microscope images, Rayleigh contrast stretching is developed and employed. First, re-scaling is performed on the input image histograms with Rayleigh algorithm. Then, contrast stretching or contrast adjustment is implemented to improve the images while reducing the contrast charging artifacts. This technique has been compared to some existing histogram equalization (HE) extension techniques: recursive sub-image HE, contrast stretching dynamic HE, multipeak HE and recursive mean separate HE. Other post processing methods, such as wavelet approach, spatial filtering, and exponential contrast stretching, are compared as well. Overall, the proposed method produces better image compensation in reducing charging artifacts. Copyright © 2011 Wiley Periodicals, Inc.

  20. 600 Volt Stretched Lens Array for Solar Electric Propulsion, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past six years, ENTECH, Auburn, NASA, and other organizations have developed a new space photovoltaic array called the Stretched Lens Array (SLA), which...

  1. An economic analysis of stretch-out for Angra-1 reactor

    International Nuclear Information System (INIS)

    Sakai, M.

    1989-01-01

    An application of NUCOST code for calculating nuclear energy cost is presented. Ann optimization of stretch-out for Angra-1 reactor based on international costs of nuclear fuel, operation and maintenance is done. (M.C.K.)

  2. Modification of permeability of frog perineurium to [14C]-sucrose by stretch and hypertonicity

    International Nuclear Information System (INIS)

    Weerasuriya, A.; Rapoport, S.I.; Taylor, R.E.

    1979-01-01

    An in vitro method has been developed to determine quantitatively the permeability of the perineurium to radiotracers at room temperature. The permeability to [ 14 C]sucrose of the isolated perineurium of the sciatic nerve of the frog, Rana pipiens, was measured at rest length, when the perineurium was stretched and after the perineurium had been subjected to hypertonic treatment. Mean permeability at rest length was calculated to be 5.6 +- 0.27 (S.E.M., n=45)x10 -7 cm/sec, and both stretch and hypertonic treatment increased the permeability. A 10% stretch increased permeability reversibly, whereas a 20% stretch or immersion of the perineurium in a hypertonic bath increased permeability irreversibly. Altered permeability under these conditions might be related to changes in the ultrastructure of tight junctions in the perineurium. (Auth.)

  3. Anomalous growth and dissipation of the magnetic field in a turbulent flow with stretches

    Energy Technology Data Exchange (ETDEWEB)

    Gvaramadze, V V; Lominadze, J G; Ruzmaikin, A A; Sokolov, D D

    1987-04-01

    The magnetic field evolution in helical turbulence with stretches is investigated. It is shown that heavy concentrations of the magnetic field appear under definite conditions. The results are consistent with numerical experiments.

  4. Anomalous growth and dissipation of the magnetic field in a turbulent flow with stretches

    International Nuclear Information System (INIS)

    Gvaramadze, V.V.; Lominadze, J.G.; Ruzmaikin, A.A.; Sokolov, D.D.

    1987-01-01

    The magnetic field evolution in helical turbulence with stretches is investigated. It is shown that heavy concentrations of the magnetic field appear under definite conditions. The results are consistent with numerical experiments

  5. Transient photoresponse in amorphous In-Ga-Zn-O thin films under stretched exponential analysis

    Science.gov (United States)

    Luo, Jiajun; Adler, Alexander U.; Mason, Thomas O.; Bruce Buchholz, D.; Chang, R. P. H.; Grayson, M.

    2013-04-01

    We investigated transient photoresponse and Hall effect in amorphous In-Ga-Zn-O thin films and observed a stretched exponential response which allows characterization of the activation energy spectrum with only three fit parameters. Measurements of as-grown films and 350 K annealed films were conducted at room temperature by recording conductivity, carrier density, and mobility over day-long time scales, both under illumination and in the dark. Hall measurements verify approximately constant mobility, even as the photoinduced carrier density changes by orders of magnitude. The transient photoconductivity data fit well to a stretched exponential during both illumination and dark relaxation, but with slower response in the dark. The inverse Laplace transforms of these stretched exponentials yield the density of activation energies responsible for transient photoconductivity. An empirical equation is introduced, which determines the linewidth of the activation energy band from the stretched exponential parameter β. Dry annealing at 350 K is observed to slow the transient photoresponse.

  6. Optimization of path length stretching in Monte Carlo calculations for non-leakage problems

    Energy Technology Data Exchange (ETDEWEB)

    Hoogenboom, J.E. [Delft Univ. of Technology (Netherlands)

    2005-07-01

    Path length stretching (or exponential biasing) is a well known variance reduction technique in Monte Carlo calculations. It can especially be useful in shielding problems where particles have to penetrate a lot of material before being tallied. Several authors sought for optimization of the path length stretching parameter for detection of the leakage of neutrons from a slab. Here the adjoint function behaves as a single exponential function and can well be used to determine the stretching parameter. In this paper optimization is sought for a detector embedded in the system, which changes the adjoint function in the detector drastically. From literature it is known that the combination of path length stretching and angular biasing can result in appreciable variance reduction. However, angular biasing is not generally available in general purpose Monte Carlo codes and therefore we want to restrict ourselves to the application of pure path length stretching and finding optimum parameters for that. Nonetheless, the starting point for our research is the zero-variance scheme. In order to study the solution in detail the simplified monoenergetic two-direction model is adopted, which allows analytical solutions and can still be used in a Monte Carlo simulation. Knowing the zero-variance solution analytically, it is shown how optimum path length stretching parameters can be derived from it. It results in path length shrinking in the detector. Results for the variance in the detector response are shown in comparison with other patterns for the stretching parameter. The effect of anisotropic scattering on the path length stretching parameter is taken into account. (author)

  7. Cyclic mechanical stretch enhances BMP9-induced osteogenic differentiation of mesenchymal stem cells.

    Science.gov (United States)

    Song, Yang; Tang, Yinhong; Song, Jinlin; Lei, Mingxing; Liang, Panpan; Fu, Tiwei; Su, Xudong; Zhou, Pengfei; Yang, Li; Huang, Enyi

    2018-04-01

    The purpose of this study was to investigate whether mechanical stretch can enhance the bone morphogenetic protein 9 (BMP9)-induced osteogenic differentiation in MSCs. Recombinant adenoviruses were used to overexpress the BMP9 in C3H10T1/2 MSCs. Cells were seeded onto six-well BioFlex collagen I-coated plates and subjected to cyclic mechanical stretch [6% elongation at 60 cycles/minute (1 Hz)] in a Flexercell FX-4000 strain unit for up to 12 hours. Immunostaining and confocal microscope were used to detect cytoskeleton organization. Cell cycle progression was checked by flow cytometry. Alkaline phosphatase activity was measured with a Chemiluminescence Assay Kit and was quantified with a histochemical staining assay. Matrix mineralization was examined by Alizarin Red S Staining. Mechanical stretch induces cytoskeleton reorganization and inhibits cell proliferation by preventing cells entry into S phase of the cell cycle. Although mechanical stretch alone does not induce the osteogenic differentiation of C3H10T1/2 MSCs, co-stimulation with mechanical stretch and BMP9 enhances alkaline phosphatase activity. The expression of key lineage-specific regulators (e.g., osteocalcin (OCN), SRY-related HMG-box 9, and runt-related transcription factor 2) is also increased after the co-stimulation, compared to the mechanical stretch stimulation along. Furthermore, mechanical stretch augments the BMP9-mediated bone matrix mineralization of C3H10T1/2 MSCs. Our results suggest that mechanical stretch enhances BMP9-induced osteoblastic lineage specification in C3H10T1/2 MSCs.

  8. A Systematic Review on the Effect of Mechanical Stretch on Hypertrophic Scars after Burn Injuries

    Directory of Open Access Journals (Sweden)

    Yu-ting Zhang

    2017-06-01

    Conclusion: From extensive literature search, there was no strong evidence indicating the positive effect of mechanical stretch using stretching exercise, massage, or splinting on hypertrophic scars. A firm conclusion cannot be drawn for the discrepancy of outcome measures and varied effectiveness. Most of the included studies lacked objective evaluation or control group for comparison. Further high quality studies with larger sample size and using standardized measurements are needed.

  9. Muscle oxygenation and fascicle length during passive muscle stretching in ballet-trained subjects.

    Science.gov (United States)

    Otsuki, A; Fujita, E; Ikegawa, S; Kuno-Mizumura, M

    2011-07-01

    Muscle stretching transiently decreases muscle-blood flow corresponding to a muscle extension. It may disturb a balance between muscular oxygen demand and oxygen supply to muscles and reduce muscle oxygenation. However, muscle-stretching training may improve blood circulatory condition, resulting in the maintained muscle oxygenation during muscle stretching. The aim of this study was to investigate changes in muscle-blood volume (tHb) and tissue oxygenation index (TOI) during muscle stretching determined by using near-infrared spectroscopy (NIRS) in ballet-trained (BT) and untrained (C) subjects. 11 BT women who regularly perform muscle stretching and 11 C women participated in this study. Fascicle lengths, tHb and TOI in the tibialis anterior muscle were measured during passive plantar flexion from ankle joint angles of 120° (baseline) to 140°, 160°, the maximal comfortable position without pain (CP), and the maximal position (MP). At 160°, the % fascicle-length change from baseline was significantly lower in the BT than the C group, however, for the changes in tHb and TOI the significant interaction effect between the 2 groups was not detected. On the other hand, although the increases in the fascicle length from baseline to CP and MP were greater in BT than C, the tHb and TOI reductions were comparable between groups. We concluded that it appears that BT can extend their muscles without excessive reduction in muscle-blood volume and muscle oxygenation at relatively same but absolutely greater muscle-stretching levels than C. The attenuation in these indices during high-level muscle stretching may be associated with the repetitive muscle stretching of long-term ballet training. © Georg Thieme Verlag KG Stuttgart · New York.

  10. Thermal evolution of the CO stretching band in carboxy-myoglobin in the light of neutron scattering and molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Cordone, Lorenzo [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo and CNISM, Via Archirafi 36, I-90123 Palermo (Italy)], E-mail: cordone@fisica.unipa.it; Cottone, Grazia; Giuffrida, Sergio; Librizzi, Fabio [Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo and CNISM, Via Archirafi 36, I-90123 Palermo (Italy)

    2008-04-18

    As it is well known, the thermal behaviour of the CO stretching band in MbCO reflects the interconversion among protein's taxonomic and lower tier substates. We compare here FTIR data on the thermal behaviour of the CO stretching band in MbCO embedded in non-liquid, water-trehalose matrixes, and neutron scattering data on dry and hydrated proteins and nucleic acids. The comparison, also in the light of simulative data, gives relevant information on the relationship between the mean square displacements of hydrogen atoms and the heme pocket thermal rearrangements in MbCO, as experienced by the bound CO, in the temperature region 100-200 K, and at higher temperature when large scale protein motions take place, following the so-called dynamic transition. The reported results point out how FTIR is a useful tool to study the protein internal dynamics, and complement information from neutron scattering measurements.

  11. An Analysis of Pathological Activities of CCN Proteins in Joint Disorders: Mechanical Stretch-Mediated CCN2 Expression in Cultured Meniscus Cells.

    Science.gov (United States)

    Furumatsu, Takayuki; Ozaki, Toshifumi

    2017-01-01

    The multifunctional growth factor CYR61/CTGF/NOV (CCN) 2, also known as connective tissue growth factor, regulates cellular proliferation, differentiation, and tissue regeneration. Recent literatures have described important roles of CCN2 in the meniscus metabolism. However, the mechanical stress-mediated transcriptional regulation of CCN2 in the meniscus remains unclear. The meniscus is a fibrocartilaginous tissue that controls complex biomechanics of the knee joint. Therefore, the injured unstable meniscus has a poor healing potential especially in the avascular inner region. In addition, dysfunction of the meniscus correlates with the progression of degenerative knee joint disorders and joint space narrowing. Here, we describe an experimental approach that investigates the distinct cellular behavior of inner and outer meniscus cells in response to mechanical stretch. Our experimental model can analyze the relationships between stretch-induced CCN2 expression and its functional role in the meniscus homeostasis.

  12. Risk Aversion in Game Shows

    DEFF Research Database (Denmark)

    Andersen, Steffen; Harrison, Glenn W.; Lau, Morten I.

    2008-01-01

    We review the use of behavior from television game shows to infer risk attitudes. These shows provide evidence when contestants are making decisions over very large stakes, and in a replicated, structured way. Inferences are generally confounded by the subjective assessment of skill in some games......, and the dynamic nature of the task in most games. We consider the game shows Card Sharks, Jeopardy!, Lingo, and finally Deal Or No Deal. We provide a detailed case study of the analyses of Deal Or No Deal, since it is suitable for inference about risk attitudes and has attracted considerable attention....

  13. Measuring performance at trade shows

    DEFF Research Database (Denmark)

    Hansen, Kåre

    2004-01-01

    Trade shows is an increasingly important marketing activity to many companies, but current measures of trade show performance do not adequately capture dimensions important to exhibitors. Based on the marketing literature's outcome and behavior-based control system taxonomy, a model is built...... that captures a outcome-based sales dimension and four behavior-based dimensions (i.e. information-gathering, relationship building, image building, and motivation activities). A 16-item instrument is developed for assessing exhibitors perceptions of their trade show performance. The paper presents evidence...

  14. Caspase-12 is involved in stretch-induced apoptosis mediated endoplasmic reticulum stress.

    Science.gov (United States)

    Zhang, Qiang; Liu, Jianing; Chen, Shulan; Liu, Jing; Liu, Lijuan; Liu, Guirong; Wang, Fang; Jiang, Wenxin; Zhang, Caixia; Wang, Shuangyu; Yuan, Xiao

    2016-04-01

    It is well recognized that mandibular growth, which is caused by a variety of functional appliances, is considered to be the result of both neuromuscular and skeletal adaptations. Accumulating evidence has demonstrated that apoptosis plays an important role in the adaptation of skeletal muscle function. However, the underlying mechanism of apoptosis that is induced by stretch continues to be incompletely understood. Endoplasmic reticulum stress (ERS), a newly defined signaling pathway, initiates apoptosis. This study seeks to determine if caspase-12 is involved in stretch-induced apoptosis mediated endoplasmic reticulum stress in myoblast and its underlying mechanism. Apoptosis was assessed by Hochest staining, DAPI staining and annexin V binding and PI staining. ER chaperones, such as GRP78, CHOP and caspase-12, were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Furthermore, caspase-12 inhibitor was used to value the mechanism of the caspase-12 pathway. Apoptosis of myoblast, which is subjected to cyclic stretch, was observed in a time-dependent manner. We found that GRP78 mRNA and protein were significantly increased and CHOP and caspase-12 were activated in myoblast that was exposed to cyclic stretch. Caspase-12 inhibition reduced stretch-induced apoptosis, and caspase-12 activated caspase-3 to induce apoptosis. We concluded that caspase-12 played an important role in stretch-induced apoptosis that is associated by endoplasmic reticulum stress by activating caspase-3.

  15. Conjugate Heat Transfer of Mixed Convection for Viscoelastic Fluid Past a Stretching Sheet

    Directory of Open Access Journals (Sweden)

    Kai-Long Hsiao

    2007-01-01

    Full Text Available A conjugate heat transfer problem of a second-grade viscoelastic fluid past a stretching sheet has been studied. Governing equations include heat conduction equation of a stretching sheet, continuity equation, momentum equation, and energy equation of a second-grade fluid, analyzed by a combination of a series expansion method, the similarity transformation, and a second-order accurate finite-difference method. These solutions are used to iterate with the heat conduction equation of the stretching sheet to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. Ranges of dimensionless parameters, the Prandtl number Pr, the elastic number E and the conduction-convection coefficient Ncc are from 0.001 to 10, 0.0001 to 0.01, and 0.5 to 2.0, respectively. A parameter G, which is used to represent the dominance of the buoyant effect, is present in governing equations. Results indicated that elastic effect in the flow could increase the local heat transfer coefficient and enhance the heat transfer of a stretching sheet. In addition, same as the results from Newtonian fluid flow and conduction analysis of a stretching sheet, a better heat transfer is obtained with a larger Ncc, G, and E.

  16. Acute effect of different time periods of passive static stretching on the hamstring flexibility.

    Science.gov (United States)

    Cini, Anelize; de Vasconcelos, Gabriela Souza; Lima, Claudia Silveira

    2017-01-01

    Several factors are associated with the presence of chronic low back pain; one of them is the flexibility of the hamstring muscles that influences the posture of the pelvic spine. Investigate the influence of two different time periods of passive static stretching on the flexibility of the hamstring. Forty-six physiotherapy students were divided into two groups performing stretching exercises: 30 s and 60 s duration. The collections consisted of: (1) pre-test: evaluation of the flexibility of the hip and knee, using a manual goniometer by means of the following tests: Straight Leg Raise Test (SLR), Passive Hip Flexion Test (PHFT) and Modified Knee Extension Test (MKET), (2) intervention: stretching with different runtimes, (3) post-test: reappraisal of flexibility, conducted immediately after the intervention. Significant difference was observed intra groups, group that did stretching exercises lasting 30 seconds (G30) (SLR p = 0.000. PHFT p = 0.003 and MKET p = 0.000) and group that did stretching exercises lasting 60 seconds (G60) (SLR p = 0.000. PHFT p = 0.001 and MKET p = 0.002). Comparing the groups, no significant difference was found (SLR p = 0.307; PHFT p = 0.904; MKET p = 0.132). Thus it can be inferred that 30 seconds are sufficient for increased flexibility of young women. Therefore the time-treatment sessions can be optimized. Only the acute effect of stretching was observed; further investigation of the long-term effect is required.

  17. Biochemical analysis of force-sensitive responses using a large-scale cell stretch device.

    Science.gov (United States)

    Renner, Derrick J; Ewald, Makena L; Kim, Timothy; Yamada, Soichiro

    2017-09-03

    Physical force has emerged as a key regulator of tissue homeostasis, and plays an important role in embryogenesis, tissue regeneration, and disease progression. Currently, the details of protein interactions under elevated physical stress are largely missing, therefore, preventing the fundamental, molecular understanding of mechano-transduction. This is in part due to the difficulty isolating large quantities of cell lysates exposed to force-bearing conditions for biochemical analysis. We designed a simple, easy-to-fabricate, large-scale cell stretch device for the analysis of force-sensitive cell responses. Using proximal biotinylation (BioID) analysis or phospho-specific antibodies, we detected force-sensitive biochemical changes in cells exposed to prolonged cyclic substrate stretch. For example, using promiscuous biotin ligase BirA* tagged α-catenin, the biotinylation of myosin IIA increased with stretch, suggesting the close proximity of myosin IIA to α-catenin under a force bearing condition. Furthermore, using phospho-specific antibodies, Akt phosphorylation was reduced upon stretch while Src phosphorylation was unchanged. Interestingly, phosphorylation of GSK3β, a downstream effector of Akt pathway, was also reduced with stretch, while the phosphorylation of other Akt effectors was unchanged. These data suggest that the Akt-GSK3β pathway is force-sensitive. This simple cell stretch device enables biochemical analysis of force-sensitive responses and has potential to uncover molecules underlying mechano-transduction.

  18. Cross-bridge mechanism of residual force enhancement after stretching in a skeletal muscle.

    Science.gov (United States)

    Tamura, Youjiro

    2018-01-01

    A muscle model that uses a modified Langevin equation with actomyosin potentials was used to describe the residual force enhancement after active stretching. Considering that the new model uses cross-bridge theory to describe the residual force enhancement, it is different from other models that use passive stretching elements. Residual force enhancement was simulated using a half sarcomere comprising 100 myosin molecules. In this paper, impulse is defined as the integral of an excess force from the steady isometric force over the time interval for which a stretch is applied. The impulse was calculated from the force response due to fast and slow muscle stretches to demonstrate the viscoelastic property of the cross-bridges. A cross-bridge mechanism was proposed as a way to describe the residual force enhancement on the basis of the impulse results with reference to the compliance of the actin filament. It was assumed that the period of the actin potential increased by 0.5% and the amplitude of the potential decreased by 0.5% when the half sarcomere was stretched by 10%. The residual force enhancement after 21.0% sarcomere stretching was 6.9% of the maximum isometric force of the muscle; this value was due to the increase in the number of cross-bridges.

  19. Barriers to performing stretching exercises among Korean-Chinese female migrant workers in Korea.

    Science.gov (United States)

    Lee, Hyeonkyeong; Wilbur, JoEllen; Chae, Duckhee; Lee, Kyongeun; Lee, Meenhye

    2015-01-01

    The purpose of this study was to investigate the barriers to performing stretching exercise experienced by Korean-Chinese female migrant workers during a community-based 12-week stretching exercise intervention trial. Qualitative secondary data analysis was conducted using telephone counseling interview transcripts from 27 middle-aged, Korean-Chinese migrant women workers. A semistructured interview question asking barriers to performing stretching exercise was given to women who did not adhere to recommended stretching exercise. During the 12-week home-based stretching exercise intervention trial, six telephone calls were made to participants biweekly to elicit barriers to performing stretching exercise. Directed content analysis approach was utilized using three barrier categories: intrapersonal, interpersonal, and work-related environmental factors based on the ecological model. Participants experienced an average of 2.5 barriers during the study period. Intrapersonal barriers included lack of time and lack of motivation, and interpersonal barriers included no family to provide support and also a feeling resistance from coworkers. Work-related environmental barriers included frequent job changes, long working hours, lack of rest time, and unpredictable job demands. The findings highlight that migrant workers in Korea face unique work-related difficulties which present barriers to exercise. © 2014 Wiley Periodicals, Inc.

  20. Occurrence and fate of pesticides in the Argentine stretch of the Paraguay-Paraná basin.

    Science.gov (United States)

    Etchegoyen, M A; Ronco, A E; Almada, P; Abelando, M; Marino, D J

    2017-02-01

    The Argentine stretch of the del Plata basin crosses regions devoted to extensive and intensive agriculture mostly with chemical pest control. The utilization of pesticides in the region has increased 900% in the last two decades associated with the introduction of biotech crops and direct-seeding techniques. Our objective was to study the occurrence, concentration, and fate of pesticides in surface water and bottom sediments of the principal tributaries and main watercourse of the Paraguay-Paraná River. We sampled 22 sites in the distal positions of the main affluents and main watercourse of the Paraná and report here results from two monitoring campaigns (2010-2012). Surface water and bottom sediments were analyzed according to standardized methods by matrix-solid-phase dispersion and liquid-liquid extraction, respectively. Twenty-three pesticide compounds were analyzed by gas chromatography. The results from both campaigns indicated a generalized but variable distribution in the concentrations detected throughout the basin. The ranges of total measured pesticide concentrations in water and sediments were, respectively, 0.004-6.62 μg/l and 0.16-221.3 μg/kg dry weight. Endosulfans, cypermethrin, and chlorpyrifos were ubiquitous compounds in both environmental compartments and quantitatively the most relevant. All concentrations detected in water were over the recommended guidelines for the protection of aquatic biota. The partitioning indicated a higher affinity for the sediments. Agricultural activity is the source of pesticide-pollution loads, transported by tributaries that reach the main watercourse and alter the quality of the aquatic ecosystem.

  1. High resolution infrared and Raman spectra of 13C12CD2: The CD stretching fundamentals and associated combination and hot bands

    International Nuclear Information System (INIS)

    Di Lonardo, G.; Fusina, L.; Canè, E.; Tamassia, F.; Martínez, R. Z.; Bermejo, D.

    2015-01-01

    Infrared and Raman spectra of mono 13 C fully deuterated acetylene, 13 C 12 CD 2 , have been recorded and analysed to obtain detailed information on the C—D stretching fundamentals and associated combination, overtone, and hot bands. Infrared spectra were recorded at an instrumental resolution ranging between 0.006 and 0.01 cm −1 in the region 1800–7800 cm −1 . Sixty new bands involving the ν 1 and ν 3 C—D stretching modes also associated with the ν 4 and ν 5 bending vibrations have been observed and analysed. In total, 5881 transitions have been assigned in the investigated spectral region. In addition, the Q branch of the ν 1 fundamental was recorded using inverse Raman spectroscopy, with an instrumental resolution of about 0.003 cm −1 . The transitions relative to each stretching mode, i.e., the fundamental band, its first overtone, and associated hot and combination bands involving bending states with υ 4 + υ 5 up to 2 were fitted simultaneously. The usual Hamiltonian appropriate to a linear molecule, including vibration and rotation l-type and the Darling–Dennison interaction between υ 4 = 2 and υ 5 = 2 levels associated with the stretching states, was adopted for the analysis. The standard deviation for each global fit is ≤0.0004 cm −1 , of the same order of magnitude of the measurement precision. Slightly improved parameters for the bending and the ν 2 manifold have been also determined. Precise values of spectroscopic parameters deperturbed from the resonance interactions have been obtained. They provide quantitative information on the anharmonic character of the potential energy surface, which can be useful, in addition to those reported in the literature, for the determination of a general anharmonic force field for the molecule. Finally, the obtained values of the Darling–Dennison constants can be valuable for understanding energy flows between independent vibrations

  2. Effect of antisymmetric C–H stretching excitation on the dynamics of O({sup 1}D) + CH{sub 4} → OH + CH{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Huilin; Yang, Jiayue; Zhang, Dong; Shuai, Quan; Jiang, Bo [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Dai, Dongxu; Wu, Guorong, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn; Yang, Xueming, E-mail: wugr@dicp.ac.cn, E-mail: xmyang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-04-21

    The effect of antisymmetric C–H stretching excitation of CH{sub 4} on the dynamics and reactivity of the O({sup 1}D) + CH{sub 4} → OH + CD{sub 3} reaction at the collision energy of 6.10 kcal/mol has been investigated using the crossed-beam and time-sliced velocity map imaging techniques. The antisymmetric C–H stretching mode excited CH{sub 4} molecule was prepared by direct infrared excitation. From the measured images of the CH{sub 3} products with the infrared laser on and off, the product translational energy and angular distributions were derived for both the ground and vibrationally excited reactions. Experimental results show that the vibrational energy of the antisymmetric stretching excited CH{sub 4} reagent is channeled exclusively into the vibrational energy of the OH co-products and, hence, the OH products from the excited-state reaction are about one vibrational quantum hotter than those from the ground-state reaction, and the product angular distributions are barely affected by the vibrational excitation of the CH{sub 4} reagent. The reactivity was found to be suppressed by the antisymmetric stretching excitation of CH{sub 4} for all observed CH{sub 3} vibrational states. The degree of suppression is different for different CH{sub 3} vibrational states: the suppression is about 40%–60% for the ground state and the umbrella mode excited CH{sub 3} products, while for the CH{sub 3} products with one quantum symmetric stretching mode excitation, the suppression is much less pronounced. In consequence, the vibrational state distribution of the CH{sub 3} product from the excited-state reaction is considerably different from that of the ground-state reaction.

  3. Effect of stretching program in an industrial workplace on hamstring flexibility and sagittal spinal posture of adult women workers: a randomized controlled trial.

    Science.gov (United States)

    Muyor, José M; López-Miñarro, Pedro A; Casimiro, Antonio J

    2012-01-01

    To determine the effect of a stretching program performed in the workplace on the hamstring muscle extensibility and sagittal spinal posture of adult women. Fifty-eight adult women volunteers (mean age of 44.23 ± 8.87 years) from a private fruit and vegetable company were randomly assigned to experimental (n=27) or control (n=31) groups. The experimental group performed three exercises of hamstrings stretching of 20 seconds per exercise, three sessions a week for a period of 12 weeks. The control group did not participate in any hamstring stretching program. Hamstring flexibility was evaluated through the passive straight leg raise test and toe-touch test, performed both before and after the stretching program. Thoracic and lumbar curvatures and pelvic inclination were measured in relaxed standing and toe-touch test with a Spinal Mouse. Significant increases (p < 0.01) in toe-touch score and straight leg raise angle (in both legs) were found in the experimental group during post-test, while the control group showed a non-significant decrease for both toe-touch score and straight leg raise test. A significant decrease in thoracic curve and significant increase in pelvic inclination were found in the toe-touch test for the experimental group (p <0.05). However, no significant changes were found in standing posture for any group. Hamstring stretching exercises performed in the working place are effective for increasing hamstring muscle extensibility. This increase generates a more aligned thoracic curve and more anterior pelvic inclination when maximal trunk flexion is performed.

  4. Convective Heat Transfer Scaling of Ignition Delay and Burning Rate with Heat Flux and Stretch Rate in the Equivalent Low Stretch Apparatus

    Science.gov (United States)

    Olson, Sandra

    2011-01-01

    To better evaluate the buoyant contributions to the convective cooling (or heating) inherent in normal-gravity material flammability test methods, we derive a convective heat transfer correlation that can be used to account for the forced convective stretch effects on the net radiant heat flux for both ignition delay time and burning rate. The Equivalent Low Stretch Apparatus (ELSA) uses an inverted cone heater to minimize buoyant effects while at the same time providing a forced stagnation flow on the sample, which ignites and burns as a ceiling fire. Ignition delay and burning rate data is correlated with incident heat flux and convective heat transfer and compared to results from other test methods and fuel geometries using similarity to determine the equivalent stretch rates and thus convective cooling (or heating) rates for those geometries. With this correlation methodology, buoyant effects inherent in normal gravity material flammability test methods can be estimated, to better apply the test results to low stretch environments relevant to spacecraft material selection.

  5. Plantar fascia-specific stretching versus radial shock-wave therapy as initial treatment of plantar fasciopathy.

    Science.gov (United States)

    Rompe, Jan D; Cacchio, Angelo; Weil, Lowell; Furia, John P; Haist, Joachim; Reiners, Volker; Schmitz, Christoph; Maffulli, Nicola

    2010-11-03

    Whether plantar fascia-specific stretching or shock-wave therapy is effective as an initial treatment for proximal plantar fasciopathy remains unclear. The aim of this study was to test the null hypothesis of no difference in the effectiveness of these two forms of treatment for patients who had unilateral plantar fasciopathy for a maximum duration of six weeks and which had not been treated previously. One hundred and two patients with acute plantar fasciopathy were randomly assigned to perform an eight-week plantar fascia-specific stretching program (Group I, n = 54) or to receive repetitive low-energy radial shock-wave therapy without local anesthesia, administered weekly for three weeks (Group II, n = 48). All patients completed the seven-item pain subscale of the validated Foot Function Index and a patient-relevant outcome questionnaire. Patients were evaluated at baseline and at two, four, and fifteen months after baseline. The primary outcome measures were a mean change in the Foot Function Index sum score at two months after baseline, a mean change in item 2 (pain during the first few steps of walking in the morning) on this index, and satisfaction with treatment. No difference in mean age, sex, weight, or duration of symptoms was found between the groups at baseline. At two months after baseline, the Foot Function Index sum score showed significantly greater changes for the patients managed with plantar fascia-specific stretching than for those managed with shock-wave therapy (p plantar fascia is superior to repetitive low-energy radial shock-wave therapy for the treatment of acute symptoms of proximal plantar fasciopathy.

  6. Coupling Langevin Dynamics With Continuum Mechanics: Exposing the Role of Sarcomere Stretch Activation Mechanisms to Cardiac Function

    Directory of Open Access Journals (Sweden)

    Takumi Washio

    2018-04-01

    Full Text Available High-performance computing approaches that combine molecular-scale and macroscale continuum mechanics have long been anticipated in various fields. Such approaches may enrich our understanding of the links between microscale molecular mechanisms and macroscopic properties in the continuum. However, there have been few successful examples to date owing to various difficulties associated with overcoming the large spatial (from 1 nm to 10 cm and temporal (from 1 ns to 1 ms gaps between the two scales. In this paper, we propose an efficient parallel scheme to couple a microscopic model using Langevin dynamics for a protein motor with a finite element continuum model of a beating heart. The proposed scheme allows us to use a macroscale time step that is an order of magnitude longer than the microscale time step of the Langevin model, without loss of stability or accuracy. This reduces the overhead required by the imbalanced loads of the microscale computations and the communication required when switching between scales. An example of the Langevin dynamics model that demonstrates the usefulness of the coupling approach is the molecular mechanism of the actomyosin system, in which the stretch-activation phenomenon can be successfully reproduced. This microscopic Langevin model is coupled with a macroscopic finite element ventricle model. In the numerical simulations, the Langevin dynamics model reveals that a single sarcomere can undergo spontaneous oscillation (15 Hz accompanied by quick lengthening due to cooperative movements of the myosin molecules pulling on the common Z-line. Also, the coupled simulations using the ventricle model show that the stretch-activation mechanism contributes to the synchronization of the quick lengthening of the sarcomeres at the end of the systolic phase. By comparing the simulation results given by the molecular model with and without the stretch-activation mechanism, we see that this synchronization contributes to

  7. Tokyo Motor Show 2003; Tokyo Motor Show 2003

    Energy Technology Data Exchange (ETDEWEB)

    Joly, E.

    2004-01-01

    The text which follows present the different techniques exposed during the 37. Tokyo Motor Show. The report points out the great tendencies of developments of the Japanese automobile industry. The hybrid electric-powered vehicles or those equipped with fuel cells have been highlighted by the Japanese manufacturers which allow considerable budgets in the research of less polluting vehicles. The exposed models, although being all different according to the manufacturer, use always a hybrid system: fuel cell/battery. The manufacturers have stressed too on the intelligent systems for navigation and safety as well as on the design and comfort. (O.M.)

  8. Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1.

    Science.gov (United States)

    Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

    2015-02-01

    Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30-50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40-50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30-40% in tension developing muscle but did not affect contraction-stimulated glucose transport in

  9. The effects of ramp stretches on active contractions in intact mammalian fast and slow muscle fibres.

    Science.gov (United States)

    Mutungi, G; Ranatunga, K W

    2001-01-01

    The effects of a ramp stretch (amplitude muscle fibre length (L0), speed twitch tension and twitch tension re-development were examined in intact mammalian (rat) fast and slow muscle fibre bundles. The experiments were done in vitro at 20 degrees C and at an initial sarcomere length of 2.68 microm. In both fibre types, a stretch applied during the rising phase of the twitch response (including the time of stimulation) increased the re-developed twitch tension (15-35%). A stretch applied before the stimulus had little or no effect on the twitch myogram in fast muscle fibres, but it increased the twitch tension (approximately 5%) in slow muscle fibres. A similar stretch had little or no effect on tetanic tension in either muscle fibre type. In general, the results indicate that the contractile-activation mechanism may be stretch sensitive and this is particularly pronounced in slow muscle fibres. Recorded at a high sampling rate and examined at an appropriate time scale, the transitory tension response to a stretch rose in at least two phases; an initial rapid tension rise to a break (break point tension, P1a) followed by a slower tension rise (apparent P2a) to a peak reached at the end of the stretch. Plotted against stretch velocity, P1a tension increased in direct proportion to stretch velocity (viscous-like) whereas, P2a tension (calculated as peak tension minus P1a tension) increased with stretch velocity to a plateau (visco-elastic). Examined at the peak of a twitch, P1a tension had a slope (viscosity coefficient) of 1.8 kN m(-2) per L0 s(-1) in fast fibres and 4.7 kN m(-2) per L0 s(-1) in slow muscle fibres. In the same preparations, P2a tension had a relaxation time of 8 ms in the fast muscle fibres and 25 ms in the slow muscle fibres. The amplitudes of both tension components scaled with the instantaneous twitch tension in qualitatively the same way as the instantaneous fibre stiffness. These fast/slow fibre type differences probably reflect differences in

  10. Regionalism, Regionalization and Regional Development

    Directory of Open Access Journals (Sweden)

    Liviu C. Andrei

    2016-03-01

    Full Text Available Sustained development is a concept associating other concepts, in its turn, in the EU practice, e.g. regionalism, regionalizing and afferent policies, here including structural policies. This below text, dedicated to integration concepts, will limit on the other hand to regionalizing, otherwise an aspect typical to Europe and to the EU. On the other hand, two aspects come up to strengthen this field of ideas, i.e. the region (al-regionalism-(regional development triplet has either its own history or precise individual outline of terms.

  11. Influence of the nematic order on the rheology and conformation of stretched comb-like liquid crystalline polymers

    Science.gov (United States)

    Fourmaux-Demange, V.; Brûlet, A.; Boué, F.; Davidson, P.; Keller, P.; Cotton, J. P.

    2000-04-01

    We have studied the rheology and the conformation of stretched comb-like liquid-crystalline polymers. Both the influence of the comb-like structure and the specific effect of the nematic interaction on the dynamics are investigated. For this purpose, two isomers of a comb-like polymetacrylate polymer, of well-defined molecular weights, were synthesized: one displays a nematic phase over a wide range of temperature, the other one has only an isotropic phase. Even with high degrees of polymerization N, between 40 and 1000, the polymer chains studied were not entangled. The stress-strain curves during the stretching and relaxation processes show differences between the isotropic and nematic comb-like polymers. They suggest that, in the nematic phase, the chain dynamics is more cooperative than for a usual linear polymer. Small-angle neutron scattering has been used in order to determine the evolution of the chain conformation after stretching, as a function of the duration of relaxation t_r. The conformation can be described with two parameters only: λ_p, the global deformation of the polymer chain, and p, the number of statistical units of locally relaxed sub-chains. For the comb-like polymer, the chain deformation is pseudo-affine: λ_p is always smaller than λ (the deformation ratio of the whole sample). In the isotropic phase, λ_p has a constant value, while p increases as t_r. This latter behavior is not that expected for non-entangled chains, in which p varies as {t_r}^{1/2} (Rouse model). In the nematic phase, λ_p decreases as a stretched exponential function of t_r, while p remains constant. The dynamics of the comb-like polymers is discussed in terms of living clusters from which junctions are produced by interactions between side chains. The nematic interaction increases the lifetime of these junctions and, strikingly, the relaxation is the same at all scales of the whole polymer chain.

  12. Reality show: um paradoxo nietzschiano

    Directory of Open Access Journals (Sweden)

    Ilana Feldman

    2011-01-01

    Full Text Available

    O fenômeno dos reality shows - e a subseqüente relação entre imagem e verdade - assenta-se sobre uma série de paradoxos. Tais paradoxos podem ser compreendidos à luz do pensamento do filósofo alemão Friedrich Nietzsche, que, através dos usos de formulações paradoxais, concebia a realidade como um mundo de pura aparência e a verdade como um acréscimo ficcional, como um efeito. A ficção é então tomada, na filosofia de Nietzsche, não em seu aspecto falsificante e desrealizador - como sempre pleiteou nossa tradição metafísica -, mas como condição necessária para que certa espécie de invenção possa operar como verdade. Sendo assim, a própria expressão reality show, através de sua formulação paradoxal, engendra explicitamente um mundo de pura aparência, em que a verdade, a parte reality da proposição, é da ordem do suplemento, daquilo que se acrescenta ficcionalmente - como um adjetivo - a show. O ornamento, nesse caso, passa a ocupar o lugar central, apontando para o efeito produzido: o efeito-de-verdade. Seguindo, então, o pensamento nietzschiano e sua atualização na contemporaneidade, investigaremos de que forma os televisivos “shows de realidade” operam paradoxalmente, em consonância com nossas paradoxais práticas culturais.

  13. Retosiban Prevents Stretch-Induced Human Myometrial Contractility and Delays Labor in Cynomolgus Monkeys.

    Science.gov (United States)

    Aye, Irving L M H; Moraitis, Alexandros A; Stanislaus, Dinesh; Charnock-Jones, D Stephen; Smith, Gordon C S

    2018-03-01

    Stretch of the myometrium promotes its contractility and is believed to contribute to the control of parturition at term and to the increased risk of preterm birth in multiple pregnancies. To determine the effects of the putative oxytocin receptor (OTR) inverse agonist retosiban on (1) the contractility of human myometrial explants and (2) labor in nonhuman primates. Human myometrial biopsies were obtained at planned term cesarean, and explants were exposed to stretch in the presence and absence of a range of drugs, including retosiban. The in vivo effects of retosiban were determined in cynomolgus monkeys. Prolonged mechanical stretch promoted myometrial extracellular signal-regulated kinase (ERK)1/2 phosphorylation. Moreover, stretch-induced stimulation of myometrial contractility was prevented by ERK1/2 inhibitors. Retosiban (10 nM) prevented stretch-induced stimulation of myometrial contractility and phosphorylation of ERK1/2. Moreover, the inhibitory effect of retosiban on stretch-induced ERK1/2 phosphorylation was prevented by coincubation with a 100-fold excess of a peptide OTR antagonist, atosiban. Compared with vehicle-treated cynomolgus monkeys, treatment with oral retosiban (100 to 150 days of gestational age) reduced the risk of spontaneous delivery (hazard ratio = 0.07, 95% confidence interval 0.01 to 0.60, P = 0.015). The OTR acts as a uterine mechanosensor, whereby stretch increases myometrial contractility through agonist-free activation of the OTR. Retosiban prevents this through inverse agonism of the OTR and, in vivo, reduced the likelihood of spontaneous labor in nonhuman primates. We hypothesize that retosiban may be an effective preventative treatment of preterm birth in high-risk multiple pregnancies, an area of unmet clinical need.

  14. Stretch activates human myometrium via ERK, caldesmon and focal adhesion signaling.

    Directory of Open Access Journals (Sweden)

    Yunping Li

    2009-10-01

    Full Text Available An incomplete understanding of the molecular mechanisms responsible for myometrial activation from the quiescent pregnant state to the active contractile state during labor has hindered the development of effective therapies for preterm labor. Myometrial stretch has been implicated clinically in the initiation of labor and the etiology of preterm labor, but the molecular mechanisms involved in the human have not been determined. We investigated the mechanisms by which gestation-dependent stretch contributes to myometrial activation, by using human uterine samples from gynecologic hysterectomies and Cesarean sections. Here we demonstrate that the Ca requirement for activation of the contractile filaments in human myometrium increases with caldesmon protein content during gestation and that an increase in caldesmon phosphorylation can reverse this inhibitory effect during labor. By using phosphotyrosine screening and mass spectrometry of stretched human myometrial samples, we identify 3 stretch-activated focal adhesion proteins, FAK, p130Cas, and alpha actinin. FAK-Y397, which signals integrin engagement, is constitutively phosphorylated in term human myometrium whereas FAK-Y925, which signals downstream ERK activation, is phosphorylated during stretch. We have recently identified smooth muscle Archvillin (SmAV as an ERK regulator. A newly produced SmAV-specific antibody demonstrates gestation-specific increases in SmAV protein levels and stretch-specific increases in SmAV association with focal adhesion proteins. Thus, whereas increases in caldesmon levels suppress human myometrium contractility during pregnancy, stretch-dependent focal adhesion signaling, facilitated by the ERK activator SmAV, can contribute to myometrial activation. These results suggest that focal adhesion proteins may present new targets for drug discovery programs aimed at regulation of uterine contractility.

  15. Unsteady convection flow and heat transfer over a vertical stretching surface.

    Science.gov (United States)

    Cai, Wenli; Su, Ning; Liu, Xiangdong

    2014-01-01

    This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient.

  16. Evaluation of heavy metal contamination using environmetrics and indexing approach for River Yamuna, Delhi stretch, India

    Directory of Open Access Journals (Sweden)

    Richa Bhardwaj

    2017-04-01

    Full Text Available The objective of the present study is to investigate the current status of heavy metal pollution in River Yamuna, Delhi stretch. The concentrations of Nickel, Cadmium, Chromium, Copper, Iron, Lead, and Zinc in water samples have been studied during December 2013–August 2015. The overall mean concentration of heavy metals was observed in the following order Fe > Cu > Zn > Ni > Cr > Pb > Cd. Correlation analysis formed two distinct groups of heavy metals highlighting similar sources. This was further corroborated by results from principal components analysis that showed similar grouping of heavy metals (Ni, Zn, Fe, Pb, Cd into PC1 having one common source for these heavy metals and PC2 (Cu, Cr having another common source. Further, our study pointed out two sites i.e. Najafgarh drain and Shahdara drain outlet in river Yamuna as the two potential sources responsible for the heavy metal contamination. Based on heavy metal pollution index value (1491.15, we concluded that our study area as a whole is critically polluted with heavy metals under study due to pollutant load from various anthropogenic activities.

  17. Mechanical regulation of stem-cell differentiation by the stretch-activated Piezo channel.

    Science.gov (United States)

    He, Li; Si, Guangwei; Huang, Jiuhong; Samuel, Aravinthan D T; Perrimon, Norbert

    2018-03-01

    Somatic stem cells constantly adjust their self-renewal and lineage commitment by integrating various environmental cues to maintain tissue homeostasis. Although numerous chemical and biological signals have been identified that regulate stem-cell behaviour, whether stem cells can directly sense mechanical signals in vivo remains unclear. Here we show that mechanical stress regulates stem-cell differentiation in the adult Drosophila midgut through the stretch-activated ion channel Piezo. We find that Piezo is specifically expressed in previously unidentified enteroendocrine precursor cells, which have reduced proliferation ability and are destined to become enteroendocrine cells. Loss of Piezo activity reduces the generation of enteroendocrine cells in the adult midgut. In addition, ectopic expression of Piezo in all stem cells triggers both cell proliferation and enteroendocrine cell differentiation. Both the Piezo mutant and overexpression phenotypes can be rescued by manipulation of cytosolic Ca 2+ levels, and increases in cytosolic Ca 2+ resemble the Piezo overexpression phenotype, suggesting that Piezo functions through Ca 2+ signalling. Further studies suggest that Ca 2+ signalling promotes stem-cell proliferation and differentiation through separate pathways. Finally, Piezo is required for both mechanical activation of stem cells in a gut expansion assay and the increase of cytosolic Ca 2+ in response to direct mechanical stimulus in a gut compression assay. Thus, our study demonstrates the existence of a specific group of stem cells in the fly midgut that can directly sense mechanical signals through Piezo.

  18. Optimizing an Intermittent Stretch Paradigm Using ERK1/2 Phosphorylation Results in Increased Collagen Synthesis in Engineered Ligaments

    Science.gov (United States)

    Paxton, Jennifer Z.; Hagerty, Paul; Andrick, Jonathan J.

    2012-01-01

    Dynamic mechanical input is believed to play a critical role in the development of functional musculoskeletal tissues. To study this phenomenon, cyclic uniaxial mechanical stretch was applied to engineered ligaments using a custom-built bioreactor and the effects of different stretch frequency, amplitude, and duration were determined. Stretch acutely increased the phosphorylation of p38 (3.5±0.74-fold), S6K1 (3.9±0.19-fold), and ERK1/2 (2.45±0.32-fold). The phosphorylation of ERK1/2 was dependent on time, rather than on frequency or amplitude, within these constructs. ERK1/2 phosphorylation was similar following stretch at frequencies from 0.1 to 1 Hz and amplitudes from 2.5% to 15%, whereas phosphorylation reached maximal levels at 10 min of stretch and returned toward basal within 60 min of stretch. Following a single 10-min bout of cyclic stretch, the cells remained refractory to a second stretch for up to 6 h. Using the phosphorylation of ERK1/2 as a guide, the optimum stretch paradigm was hypothesized to be 10 min of stretch at 2.5% of resting length repeated every 6 h. Consistent with this hypothesis, 7 days of stretch using this optimized intermittent stretch program increased the collagen content of the grafts more than a continuous stretch program (CTL=3.1%±0.44%; CONT=4.8%±0.30%; and INT=5.9%±0.56%). These results suggest that short infrequent bouts of loading are optimal for improving engineered tendon and ligament physiology. PMID:21902469

  19. The role of the entry-and-stretch phase at the different paces of race in front crawl swimming.

    Science.gov (United States)

    Samson, Mathias; Monnet, Tony; Bernard, Anthony; Lacouture, Patrick; David, Laurent

    2015-01-01

    The aim of this study was to determine the role played by the entry-and-stretch phase in the coordination of swimming, at the different paces of race. Three national level swimmers (two men and one woman) were recorded, in lateral and bottom views, in three swimming paces: sprint (50 m and 100 m), middle-distance (200 m and 400 m) and long-distance (800 m and 1500 m). Anatomical landmark positions were obtained by manual digitalisation of the videos. Computational fluid dynamics and experimental studies (with a strain gauge balance and particle image velocimetry method) were used to measure and to calculate the external forces applied to the hand and to the forearm and to visualise the flow around the profile. Entry-and-stretch is the phase which varies the most according to the swimming pace. This phase can be decomposed into two sub-phases: one, the extension forward coordinated with the insweep of the opposite arm, and another one, the rotation downward coordinated with the upsweep. Results show that, at the three paces, this phase is not propulsive and could contribute essentially to maintain the horizontal balance of the body.

  20. Effects of Mechanical Stretch on Cell Proliferation and Matrix Formation of Mesenchymal Stem Cell and Anterior Cruciate Ligament Fibroblast

    Directory of Open Access Journals (Sweden)

    Liguo Sun

    2016-01-01

    Full Text Available Mesenchymal stem cells (MSCs and fibroblasts are two major seed cells for ligament tissue engineering. To understand the effects of mechanical stimulation on these cells and to develop effective approaches for cell therapy, it is necessary to investigate the biological effects of various mechanical loading conditions on cells. In this study, fibroblasts and MSCs were tested and compared under a novel Uniflex/Bioflex culture system that might mimic mechanical strain in ligament tissue. The cells were uniaxially or radially stretched with different strains (5%, 10%, and 15% at 0.1, 0.5, and 1.0 Hz. The cell proliferation and collagen production were compared to find the optimal parameters. The results indicated that uniaxial stretch (15% at 0.5 Hz; 10% at 1.0 Hz showed positive effects on fibroblast. The uniaxial strains (5%, 10%, and 15% at 0.5 Hz and 10% strain at 1.0 Hz were favorable for MSCs. Radial strain did not have significant effect on fibroblast. On the contrary, the radial strains (5%, 10%, and 15% at 0.1 Hz had positive effects on MSCs. This study suggested that fibroblasts and MSCs had their own appropriate mechanical stimulatory parameters. These specific parameters potentially provide fundamental knowledge for future cell-based ligament regeneration.

  1. ACUTE EFFECTS OF STATIC STRETCHING, DYNAMIC EXERCISES, AND HIGH VOLUME UPPER EXTREMITY PLYOMETRIC ACTIVITY ON TENNIS SERVE PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Ertugrul Gelen

    2012-12-01

    Full Text Available The purpose of this study was to compare the acute effects of static stretching; dynamic exercises and high volume upper extremity plyometric activity on tennis serve performance. Twenty-six elite young tennis players (15.1 ± 4.2 years, 167.9 ± 5.8 cm and 61.6 ± 8.1 kg performed 4 different warm-up (WU routines in a random order on non-consecutive days. The WU methods consisted of traditional WU (jogging, rally and serve practice (TRAD; traditional WU and static stretching (TRSS; traditional WU and dynamic exercise (TRDE; and traditional WU and high volume upper extremity plyometric activity (TRPLYP. Following each WU session, subjects were tested on a tennis serve ball speed test. TRAD, TRSS, TRDE and TRPLYO were compared by repeated measurement analyses of variance and post-hoc comparisons. In this study a 1 to 3 percent increase in tennis serve ball speed was recorded in TRDE and TRPLYO when compared to TRAD (p 0.05. ICCs for ball speed showed strong reliability (0.82 to 0.93 for the ball speed measurements.The results of this study indicate that dynamic and high volume upper extremity plyometric WU activities are likely beneficial to serve speed of elite junior tennis players.

  2. Stretch-dependent slow force response in isolated rabbit myocardium is Na+ dependent.

    Science.gov (United States)

    von Lewinski, Dirk; Stumme, Burkhard; Maier, Lars S; Luers, Claus; Bers, Donald M; Pieske, Burkert

    2003-03-15

    Stretch induces functional and trophic effects in mammalian myocardium via various signal transduction pathways. We tested stretch signal transduction on immediate and slow force response (SFR) in rabbit myocardium. Experiments were performed in isolated right ventricular muscles from adult rabbit hearts (37 degrees C, 1 Hz stimulation rate, bicarbonate-buffer). Muscles were rapidly stretched from 88% of optimal length (L88) to near optimal length (L98) for functional analysis. The resulting immediate and slow increases in twitch force (first phase and SFR, respectively) were assessed at reduced [Na+]o or without and with blockade of stretch activated ion channels (SACs), angiotensin-II (AT1) receptors, endothelin-A (ET(A)) receptors, Na+/H+-exchange (NHE1), reverse mode Na+/Ca2+-exchange (NCX), or Na+/K+-ATPase. The effects of stretch on sarcoplasmic reticulum Ca2+-load were characterized using rapid cooling contractures (RCCs). Intracellular pH was measured in BCECF-AM loaded muscles, and action potential duration (APD) was assessed using floating electrodes. On average, force increased to 216+/-8% of the pre-stretch value during the immediate phase, followed by a further increase to 273+/-10% during the SFR (n=81). RCCs significantly increased during SFR, whereas pH and APD did not change. Neither inhibition of SACs, AT1, or ET(A) receptors affected the stretch-dependent immediate phase nor SFR. In contrast, SFR was reduced by NHE inhibition and almost completely abolished by reduced [Na+]o or inhibition of reverse-mode NCX, whereas increased SFR was seen after raising [Na+]i by Na+/K+-ATPase inhibition. The data demonstrate the existence of a delayed, Na+- and Ca2+-dependent but pH and APD independent SFR to stretch in rabbit myocardium. This inotropic response appears to be independent of autocrine/paracrine AT1 or ET(A) receptor activation, but mediated through stretch-induced activation of NHE and reverse mode NCX.

  3. All-passive pixel super-resolution of time-stretch imaging

    Science.gov (United States)

    Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; So, Hayden K. H.; Lam, Edmund Y.; Tsia, Kevin K.

    2017-03-01

    Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate — hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)—more than four times lower than the originally required readout rate (20 GSa/s) — is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.

  4. Acute Effect of Static Stretching on Lower Limb Movement Performance by Using STABL Virtual Reality System.

    Science.gov (United States)

    Ameer, Mariam A; Muaidi, Qassim I

    2017-07-17

    The effect of acute static stretch (ASS) on the lower limb RT has been recently questioned to decrease the risk of falling and injuries in situations requiring a rapid reaction, as in the cases of balance disturbance. The main purpose of this study was to detect the effect of ASS on the lower limb RT by using virtual reality device. Two Group Control Group design. Research laboratory. The control and experimental groups were formed randomly from sixty female university students. Each participant in the experimental group was tested before and after ASS for the quadriceps, hamstrings and planter flexor muscles, and compared with the control group with warming-up exercise only. The stretching program involved warming-up in the form of circular running inside the lab for 5 minutes followed by stretching of each muscle group thrice, to the limit of discomfort of 45 s, with resting period of 15s between stretches. The measurements included the RT of the dominant lower extremity by using the dynamic stability program, STABL Virtual Reality System (Model No. DIZ 2709, Motek Medical and Force Link Merged Co., Amsterdam). There was statistically significant reduction (F = 162, P= .00) in post-test RT between the two groups, and significant decrease in RT after stretching, in the experimental group (7.5%) (P= .00). ASS of the lower limb muscles tends to decrease the lower limb RT and improve movement performance.

  5. Prolonged passive static stretching-induced innervation zone shift in biceps brachii.

    Science.gov (United States)

    Ye, Xin; Beck, Travis W; Wages, Nathan P

    2015-05-01

    The purpose of this study was to examine the influence of a bout of repeated and prolonged passive static stretching on the innervation zone (IZ) location of the human biceps brachii muscle. Eleven men performed 12 sets of 100-s passive stretches on their biceps brachii. Before (Pre) and immediately after (Post) the stretching intervention, isometric strength was tested during the maximal voluntary contractions (MVCs) of the forearm flexors. The subjects also performed several separate isometric forearm flexion muscle actions at 30%, 50%, and 70% of their predetermined MVCs for examining the locations of the IZ at different contraction intensities. The IZ was identified through multi-channel surface electromyographic (EMG) recordings from a linear electrode array. The stretching intervention induced an average of 10% isometric strength loss for the forearm flexors (mean±SD: Pre-MVC vs. Post-MVC=332.12±59.40 N vs. 299.53±70.51 N; p<0.001). In addition, the average IZ shift was nearly 4.5 mm in average in the proximal direction. However, this shift was not specific to the contraction intensity. We believe that the IZ shift was caused by the elongation of the entire muscle-tendon unit in the proximal direction. Therefore, caution should be taken when using surface EMG technique to examine possible changes in the EMG variables after a stretching protocol, as these variables can be contaminated by the shift of the IZ.

  6. Assessing the stretch-blow moulding FE simulation of PET over a large process window

    Science.gov (United States)

    Nixon, J.; Menary, G. H.; Yan, S.

    2017-10-01

    Injection stretch blow moulding has been extensively researched for numerous years and is a well-established method of forming thin-walled containers. This paper is concerned with validating the finite element analysis of the stretch-blow-moulding (SBM) process in an effort to progress the development of injection stretch blow moulding of poly(ethylene terephthalate). Extensive data was obtained experimentally over a wide process window accounting for material temperature, air flow rate and stretch-rod speed while capturing cavity pressure, stretch-rod reaction force, in-mould contact timing and material thickness distribution. This data was then used to assess the accuracy of the correlating FE simulation constructed using ABAQUS/Explicit solver and an appropriate user-defined viscoelastic material subroutine. Results reveal that the simulation was able to pick up the general trends of how the pressure, reaction force and in-mould contact timings vary with the variation in preform temperature and air flow rate. Trends in material thickness were also accurately predicted over the length of the bottle relative to the process conditions. The knowledge gained from these analyses provides insight into the mechanisms of bottle formation, subsequently improving the blow moulding simulation and potentially providing a reduction in production costs.

  7. Prolonged static stretching does not influence running economy despite changes in neuromuscular function.

    Science.gov (United States)

    Allison, Sarah J; Bailey, David M; Folland, Jonathan P

    2008-12-01

    The aim of this study was to examine the acute effects of prolonged static stretching (SS) on running economy. Ten male runners (VO2(peak) 60.1 +/- 7.3 ml x kg(-1) x min(-1)) performed 10 min of treadmill running at 70% VO2(peak) before and after SS and no stretching interventions. For the stretching intervention, each leg was stretched unilaterally for 40 s with each of eight different exercises and this was repeated three times. Respiratory gas exchange was measured throughout the running exercise with an automated gas analysis system. On a separate day, participants were tested for sit and reach range of motion, isometric strength and countermovement jump height before and after SS. The oxygen uptake, minute ventilation, energy expenditure, respiratory exchange ratio and heart rate responses to running were unaffected by the stretching intervention. This was despite a significant effect of SS on neuromuscular function (sit and reach range of motion, +2.7 +/- 0.6 cm; isometric strength, -5.6% +/- 3.4%; countermovement jump height -5.5% +/- 3.4%; all P influence running economy despite changes in neuromuscular function.

  8. Sequence-length variation of mtDNA HVS-I C-stretch in Chinese ethnic groups.

    Science.gov (United States)

    Chen, Feng; Dang, Yong-hui; Yan, Chun-xia; Liu, Yan-ling; Deng, Ya-jun; Fulton, David J R; Chen, Teng

    2009-10-01

    The purpose of this study was to investigate mitochondrial DNA (mtDNA) hypervariable segment-I (HVS-I) C-stretch variations and explore the significance of these variations in forensic and population genetics studies. The C-stretch sequence variation was studied in 919 unrelated individuals from 8 Chinese ethnic groups using both direct and clone sequencing approaches. Thirty eight C-stretch haplotypes were identified, and some novel and population specific haplotypes were also detected. The C-stretch genetic diversity (GD) values were relatively high, and probability (P) values were low. Additionally, C-stretch length heteroplasmy was observed in approximately 9% of individuals studied. There was a significant correlation (r=-0.961, Ppopulations. The results from the Fst and dA genetic distance matrix, neighbor-joining tree, and principal component map also suggest that C-stretch could be used as a reliable genetic marker in population genetics.

  9. Local and Systemic Changes in Pain Sensitivity After 4 Weeks of Calf Muscle Stretching in a Nonpainful Population

    DEFF Research Database (Denmark)

    Bartholdy, Cecilie; Zangger, Graziella; Hansen, Lisbeth

    2016-01-01

    BACKGROUND: Stretching is often used in clinical practice for a variety of purposes, including pain therapy. The possible mechanism behind the effect of stretching remains to be clarified. AIM: To investigate whether 4 weeks of unilateral stretching of the calf muscles would affect local...... and central pain sensitivity. METHOD: This study was a randomized assessor-blinded clinical study. Healthy participants (age 18 to 40) were included and randomized. Participants in the intervention group were instructed to perform 2 stretching exercises targeting the calf muscles; 3 times 30 seconds, 7 days...... a week for 4 weeks on the dominant leg. Participants in the control group were instructed not to do any stretching for 4 weeks. Pressure pain threshold (PPT) and temporal summation (TS) of pressure pain were measured on the stretched calf, the contra-lateral calf, and contra-lateral lower arm using...

  10. Wealth distribution, Pareto law, and stretched exponential decay of money: Computer simulations analysis of agent-based models

    Science.gov (United States)

    Aydiner, Ekrem; Cherstvy, Andrey G.; Metzler, Ralf

    2018-01-01

    We study by Monte Carlo simulations a kinetic exchange trading model for both fixed and distributed saving propensities of the agents and rationalize the person and wealth distributions. We show that the newly introduced wealth distribution - that may be more amenable in certain situations - features a different power-law exponent, particularly for distributed saving propensities of the agents. For open agent-based systems, we analyze the person and wealth distributions and find that the presence of trap agents alters their amplitude, leaving however the scaling exponents nearly unaffected. For an open system, we show that the total wealth - for different trap agent densities and saving propensities of the agents - decreases in time according to the classical Kohlrausch-Williams-Watts stretched exponential law. Interestingly, this decay does not depend on the trap agent density, but rather on saving propensities. The system relaxation for fixed and distributed saving schemes are found to be different.

  11. Distribution of guppies Poecilia reticulata (Peters, 1860 and Phalloceros caudimaculatus (Hensel, 1868 along a polluted stretch of the Paraíba do Sul River, Brazil

    Directory of Open Access Journals (Sweden)

    FG. Araújo

    Full Text Available Cyprinodontiformes fishes (guppies are widely distributed in Neotropical regions and use deteriorated microhabitats in rivers where few species can occur. This study was carried out in a stretch of the Paraíba do Sul River in bracketing a large urban-industrial complex. The aim was to assess eventual effects that the industrial complex could have on distribution of two closely related fish species of guppies, Phalloceros caudimaculatus and Poecilia reticulata. The area was divided into three zones: Z1, 40 km upriver of the major urban-industrial complex of Volta Redonda; Z2, just down river of the complex; and Z3, 30 km down river of the complex. Six sites (two in each zone were sampled monthly between November 1998 and October 1999, using a standardized fishing effort with cast net throws, trays lifts and seine hauls, covering different microhabitats, that is, riffles, pools and the proximity of the river's margins. Poecilia reticulata was widely distributed, peaking at Z2, the most polluted area, while P. caudimaculatus showed the highest abundance at Z3, being almost absent in Z1. Both species occurred in high numbers throughout the year but they were scarce between April and June. Females outnumbered males for both species in most size classes and at all sites. Juveniles were more abundant than adults, with non-pregnant females outnumbering pregnant ones. Condition factor was always higher in males than females but only males P. reticulata showed significant difference among the three zones, with the highest values at Z2. The higher number of females confirms the expectation that these species can use very polluted areas and that availability of food provided by organic loads allowed their distribution all over the area. Although these two species have shown indication of spatial separation in the study area, their similar seasonal patterns of occurrence suggest that they respond in a similar way to changes in environmental conditions.

  12. Magnetic field analysis in a suspension of gyrotactic microorganisms and nanoparticles over a stretching surface

    Energy Technology Data Exchange (ETDEWEB)

    Akbar, Noreen Sher, E-mail: noreensher@yahoo.com [DBS& H, CEME, National University of Sciences and Technology, Islamabad (Pakistan); Khan, Zafar Hayat [Department of Mathematics, University of Malakand, Dir (Lower), Khyber Pakhtunkhwa (Pakistan)

    2016-07-15

    The combine effects of magnetic field bioconvection, Brownian motion and thermophoresis on a free convection nanofluid flow over a stretching sheet containing gyrotactic microorganisms are investigated. The self-similar Buongiorno model is analyzed first time for stretching sheet numerically. The present results are compared with available data and are found in an excellent agreement. Pertinent results are presented graphically and discussed quantitatively with respect to variation in bioconvection parameters. - Highlights: • Two dimensional MHD flow in a suspension of gyrotactic microorganisms and nanoparticles over a stretching surface is discussed first paper in literature. • Governed problem for proposed model solved numerically using fourth-order Runge–Kutta–Fehlberg method. • Good agreement in comparison with previous studies. • Tabulated physical quantities and graphics of all flow profiles. • Graphics of reduced skin friction coefficient, when the different flow parameters vary.

  13. Pre-Stretched Low Equivalent Weight PFSA Membranes with Improved Fuel Cell Performance

    DEFF Research Database (Denmark)

    Zhang, Wenjing (Angela); Wycisk, Ryszard; Kish, Daniel L.

    2014-01-01

    for the morphological changes to be permanent. For 825 EW PFSA, stretching increased the polymer crystallinity by 22.5%, with a reduction in methanol permeability and a small increase in proton conductivity. In direct methanol fuel cell tests at 60◦C with 1.0 M methanol, the power density at 0.4 V with a DR = 4...... stretched 825 EW membrane (72 mW/cm2) was considerably greater than that obtained with a solution-cast membrane (28 mW/cm2) or with a commercial Nafion 117 membrane (55 mW/cm2). For 733 EW PFSA, stretching promoted the formation of ordered ionic domains leading to an increase in proton conductivity...

  14. Melting heat transfer in boundary layer stagnation-point flow towards a stretching/shrinking sheet

    International Nuclear Information System (INIS)

    Bachok, Norfifah; Ishak, Anuar; Pop, Ioan

    2010-01-01

    An analysis is carried out to study the steady two-dimensional stagnation-point flow and heat transfer from a warm, laminar liquid flow to a melting stretching/shrinking sheet. The governing partial differential equations are converted into ordinary differential equations by similarity transformation, before being solved numerically using the Runge-Kutta-Fehlberg method. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented for different values of the governing parameters. Effects of the melting parameter, stretching/shrinking parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique.

  15. Magnetohydrodynamics Carreau nanofluid flow over an inclined convective heated stretching cylinder with Joule heating

    Directory of Open Access Journals (Sweden)

    Imad Khan

    Full Text Available Current work highlights the computational aspects of MHD Carreau nanofluid flow over an inclined stretching cylinder with convective boundary conditions and Joule heating. The mathematical modeling of physical problem yields nonlinear set of partial differential equations. A suitable scaling group of variables is employed on modeled equations to convert them into non-dimensional form. The integration scheme Runge-Kutta-Fehlberg on the behalf of shooting technique is utilized to solve attained set of equations. The interesting aspects of physical problem (linear momentum, energy and nanoparticles concentration are elaborated under the different parametric conditions through graphical and tabular manners. Additionally, the quantities (local skin friction coefficient, local Nusselt number and local Sherwood number which are responsible to dig out the physical phenomena in the vicinity of stretched surface are computed and delineated by varying controlling flow parameters. Keywords: MHD, Carreau nanofluid, Inclined stretching cylinder, Joule heating, Shooting technique

  16. New approach to the exact solution of viscous flow due to stretching (shrinking and porous sheet

    Directory of Open Access Journals (Sweden)

    Azhar Ali

    Full Text Available Exact analytical solutions for the generalized stretching (shrinking of a porous surface, for the variable suction (injection velocity, is presented in this paper. The solution is generalized in the sense that the existing solutions that correspond to various stretching velocities are recovered as a special case of this study. A suitable similarity transformation is introduced to find self-similar solution of the non-linear governing equations. The flow is characterized by a few non-dimensional parameters signifying the problem completely. These parameters are such that the whole range of stretching (shrinking problems discussed earlier can be recovered by assigning appropriate values to these parameters. A key point of the whole narrative is that a number of earlier works can be abridged into one generalized problem through the introduction of a new similarity transformation and finding its exact solution encompassing all the earlier solutions. Keywords: Exact solutions, New similarities, Permeable and moving sheet

  17. Methods for thermal inactivation of pathogens in mozzarella: a comparison between stretching and pasteurization

    Directory of Open Access Journals (Sweden)

    D.C. Raimundo

    2013-04-01

    Full Text Available This study aimed to evaluate the efficiency of stretching in the reduction of pathogens when compared to milk pasteurization, the official method to ensure safe cheese production. Whole buffalo milk was contaminated with Mycobacterium fortuitum, Listeria monocytogenes, Salmonella typhimurium, and Staphylococcus aureus. Part of the milk was used in mozzarella production and the other part was submitted to holder pasteurization. Pathogens were quantified before and after thermal processing (mozzarella stretching and milk pasteurization. Pasteurization and stretching led to the following reductions in log cycles, respectively: 4.0 and 6.3 for Mycobacterium sp.; 6.0 and 8.4 for Listeria sp.; >6.8 and 4.5 for Staphylococcus sp.; and >8.2 and 7.5 for Salmonella sp.

  18. Experimental study on the deformation of erythrocytes under optically trapping and stretching

    International Nuclear Information System (INIS)

    Liu, Y.P.; Li Chuan; Lai, A.C.K.

    2006-01-01

    The mechanical behavior of erythrocytes is studied experimentally and numerically. In the experiment, prepared silica microbeads are attached to the surface of spherically swollen erythrocytes (red blood cells, RBCs) at room temperature (25 deg. C). The cells are then stretched by single laser beam via the microbeads. The relation of deformation and stretching force is quantitatively assessed by the image processing of digital pictures. Meanwhile, a physical model for an axisymmetric cell is introduced to study its deformation by different level of stretching force. By comparing the experimental and numerical data, stiffness of the cell membrane can be determined and the optimal values are found to agree with other studies by different techniques such as micropipette aspiration or high frequency electric field

  19. Developmental axon stretch stimulates neuron growth while maintaining normal electrical activity, intracellular calcium flux, and somatic morphology.

    Science.gov (United States)

    Loverde, Joseph R; Pfister, Bryan J

    2015-01-01

    Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18% applied over 5 min. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25% strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

  20. Developmental Axon Stretch Stimulates Neuron Growth While Maintaining Normal Electrical Activity, Intracellular Calcium Flux, and Somatic Morphology

    Directory of Open Access Journals (Sweden)

    Joseph R Loverde

    2015-08-01

    Full Text Available Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18 % applied over 5 minutes. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25 % strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

  1. Fourier transform infrared imaging showing reduced unsaturated lipid content in the hippocampus of a mouse model of Alzheimer's disease.

    Science.gov (United States)

    Leskovjan, Andreana C; Kretlow, Ariane; Miller, Lisa M

    2010-04-01

    Polyunsaturated fatty acids are essential to brain functions such as membrane fluidity, signal transduction, and cell survival. It is also thought that low levels of unsaturated lipid in the brain may contribute to Alzheimer's disease (AD) risk or severity. However, it is not known how accumulation of unsaturated lipids is affected in different regions of the hippocampus, which is a central target of AD plaque pathology, during aging. In this study, we used Fourier transform infrared imaging (FTIRI) to visualize the unsaturated lipid content in specific regions of the hippocampus in the PSAPP mouse model of AD as a function of plaque formation. Specifically, the unsaturated lipid content was imaged using the olefinic =CH stretching mode at 3012 cm(-1). The axonal, dendritic, and somatic layers of the hippocampus were examined in the mice at 13, 24, 40, and 56 weeks old. Results showed that lipid unsaturation in the axonal layer was significantly increased with normal aging in control (CNT) mice (p avoiding progression of the disease.

  2. Stiffness of individual quadriceps muscle assessed using ultrasound shear wave elastography during passive stretching

    Directory of Open Access Journals (Sweden)

    Jingfei Xu

    2018-04-01

    Full Text Available Background: Until recently it has not been possible to isolate the mechanical behavior of individual muscles during passive stretching. Muscle shear modulus (an index of muscle stiffness measured using ultrasound shear wave elastography can be used to estimate changes in stiffness of an individual muscle. The aims of the present study were (1 to determine the shear modulus–knee angle relationship and the slack angle of the vastus medialis oblique (VMO, rectus femoris (RF, and vastus lateralis (VL muscles; (2 to determine whether this differs between the muscles. Methods: Nine male rowers took part in the study. The shear modulus of VMO, RF, and VL muscles was measured while the quadriceps was passively stretched at 3°/s. The relationship between the muscle shear modulus and knee angle was plotted as shear modulus–knee angle curve through which the slack angle of each muscle was determined. Results: The shear modulus of RF was higher than that of VMO and VL when the muscles were stretched over 54° (all p  0.05. The slack angle was similar among the muscles: 41.3° ± 10.6°, 44.3° ± 9.1°, and 44.3° ± 5.6° of knee flexion for VMO, RF, and VL, respectively (p = 0.626. Conclusion: This is the first study to experimentally determine the muscle mechanical behavior of individual heads of the quadriceps during passive stretching. Different pattern of passive tension was observed between mono- and bi-articular muscles. Further research is needed to determine whether changes in muscle stiffness are muscle-specific in pathological conditions or after interventions such as stretching protocols. Keywords: Muscle tension, Optimal length, Shear modulus, Slack angle, Stretch, Ultrasonography, Vastus lateralis, Vastus medialis

  3. Mechanical stretch endows mesenchymal stem cells stronger angiogenic and anti-apoptotic capacities via NFκB activation

    International Nuclear Information System (INIS)

    Zhu, Zhuoli; Gan, Xueqi; Fan, Hongyi; Yu, Haiyang

    2015-01-01

    Mesenchymal stem cells (MSCs) have been broadly used for tissue regeneration and repair due to their broad differentiation potential and potent paracrine properties such as angiogenic capacity. Strategies to increase their survival rate after transplantation and the angiogenic ability are of priority for the utility of MSCs. In this study, we found that mechanical stretch (10% extension, 30 cycles/min cyclic stretch) preconditioning increase the angiogenic capacity via VEGFA induction. In addition, mechanical stretch also increases the survival rate of mesenchymal stem cells under nutrients deprivation. Consistent with the increase VEGFA expression and resistance to apoptosis, nuclear localization of NFκB activity p65 increased upon mechanical stretch. Inhibition of NFκB activity by BAY 11-708 blocks the pro-angiogenesis and anti-apoptosis function of mechanical stretch. Taken together, our findings here raise the possibility that mechanical stretch preconditioning might enhance the therapeutic efficacy of mesenchymal stem cells. - Highlights: • Mechanical stretch increases the angiogenic capacity via VEGFA induction in MSCs. • Mechanical stretch increases the survival rate of MSCs under nutrients deprivation. • Mechanical stretch manipulates MSCs via the activation of NFκB.

  4. Mechanical stretch endows mesenchymal stem cells stronger angiogenic and anti-apoptotic capacities via NFκB activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhuoli; Gan, Xueqi [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Fan, Hongyi [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Applied Mechanics, College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Yu, Haiyang, E-mail: yhyang6812@foxmail.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)

    2015-12-25

    Mesenchymal stem cells (MSCs) have been broadly used for tissue regeneration and repair due to their broad differentiation potential and potent paracrine properties such as angiogenic capacity. Strategies to increase their survival rate after transplantation and the angiogenic ability are of priority for the utility of MSCs. In this study, we found that mechanical stretch (10% extension, 30 cycles/min cyclic stretch) preconditioning increase the angiogenic capacity via VEGFA induction. In addition, mechanical stretch also increases the survival rate of mesenchymal stem cells under nutrients deprivation. Consistent with the increase VEGFA expression and resistance to apoptosis, nuclear localization of NFκB activity p65 increased upon mechanical stretch. Inhibition of NFκB activity by BAY 11-708 blocks the pro-angiogenesis and anti-apoptosis function of mechanical stretch. Taken together, our findings here raise the possibility that mechanical stretch preconditioning might enhance the therapeutic efficacy of mesenchymal stem cells. - Highlights: • Mechanical stretch increases the angiogenic capacity via VEGFA induction in MSCs. • Mechanical stretch increases the survival rate of MSCs under nutrients deprivation. • Mechanical stretch manipulates MSCs via the activation of NFκB.

  5. Modeling the electrical resistance of gold film conductors on uniaxially stretched elastomeric substrates

    Science.gov (United States)

    Cao, Wenzhe; Görrn, Patrick; Wagner, Sigurd

    2011-05-01

    The electrical resistance of gold film conductors on polydimethyl siloxane substrates at stages of uniaxial stretching is measured and modeled. The surface area of a gold conductor is assumed constant during stretching so that the exposed substrate takes up all strain. Sheet resistances are calculated from frames of scanning electron micrographs by numerically solving for the electrical potentials of all pixels in a frame. These sheet resistances agree sufficiently well with values measured on the same conductors to give credence to the model of a stretchable network of gold links defined by microcracks.

  6. Stagnation point flow towards nonlinear stretching surface with Cattaneo-Christov heat flux

    Science.gov (United States)

    Hayat, T.; Zubair, M.; Ayub, M.; Waqas, M.; Alsaedi, A.

    2016-10-01

    Here the influence of the non-Fourier heat flux in a two-dimensional (2D) stagnation point flow of Eyring-Powell liquid towards a nonlinear stretched surface is reported. The stretching surface is of variable thickness. Thermal conductivity of fluid is taken temperature-dependent. Ordinary differential systems are obtained through the implementation of meaningful transformations. The reduced non-dimensional expressions are solved for the convergent series solutions. Convergence interval is obtained for the computed solutions. Graphical results are displayed and analyzed in detail for the velocity, temperature and skin friction coefficient. The obtained results reveal that the temperature gradient enhances when the thermal relaxation parameter is increased.

  7. Plantar flexor stretch reflex responses to whole body loading/unloading during human walking

    DEFF Research Database (Denmark)

    Grey, Michael James; van Doornik, Johannes; Sinkjær, Thomas

    2002-01-01

    Numerous animal and human studies have shown that afferent information from the periphery contributes to the control of walking. In particular, recent studies have consistently shown that load receptor input is an important element of the locomotion control mechanism. The objective of this study...... perturbation during human walking. Three body load conditions were investigated: normal body load, a 30% increase in body load, and a 30% decrease in body load. Healthy subjects walked on a treadmill at approximately 3.6 km/h with the left ankle attached to a portable stretching device. Dorsiflexion...... strongly to the corrective response of the stretch reflex in the plantar flexor muscles during walking....

  8. Lamb's plane problem in a thermo-elastic micropolar medium with stretch

    Directory of Open Access Journals (Sweden)

    T. K. Chadha

    1987-01-01

    Full Text Available A study is made of the Lamb plane problem in a thermo-elastic micropolar medium with the effect of stretch. The problem is solved for an arbitrary, normal load distribution by using the double Fourier transform. The displacement components, force stress, couple stress, vector first moment and the temperature field are determined for a half space subjected to an arbitrary normal load. Two special cases of a horizontal force and a torque which are oscillating with a frequency ω have been investigated. It is shown that results of this analysis reduce to those without stretch.

  9. CNNs flag recognition preprocessing scheme based on gray scale stretching and local binary pattern

    Science.gov (United States)

    Gong, Qian; Qu, Zhiyi; Hao, Kun

    2017-07-01

    Flag is a rather special recognition target in image recognition because of its non-rigid features with the location, scale and rotation characteristics. The location change can be handled well by the depth learning algorithm Convolutional Neural Networks (CNNs), but the scale and rotation changes are quite a challenge for CNNs. Since it has good rotation and gray scale invariance, the local binary pattern (LBP) is combined with grayscale stretching and CNNs to make LBP and grayscale stretching as CNNs pretreatment, which can not only significantly improve the efficiency of flag recognition, but can also evaluate the recognition effect through ROC, accuracy, MSE and quality factor.

  10. A control scheme for filament stretching rheometers with application to polymer melts

    DEFF Research Database (Denmark)

    Román Marín, José Manuel; Huusom, Jakob Kjøbsted; Javier Alvarez, Nicolas

    2013-01-01

    We propose a new control scheme to maintain a constant strain rate of the mid-filament diameter in a filament stretching rheometer for polymer melts. The scheme is cast as a velocity algorithm and consists of a feed-back and a feed-forward contribution. The performance of the controller is demons......We propose a new control scheme to maintain a constant strain rate of the mid-filament diameter in a filament stretching rheometer for polymer melts. The scheme is cast as a velocity algorithm and consists of a feed-back and a feed-forward contribution. The performance of the controller...

  11. Stretched-exponential decay functions from a self-consistent model of dielectric relaxation

    International Nuclear Information System (INIS)

    Milovanov, A.V.; Rasmussen, J.J.; Rypdal, K.

    2008-01-01

    There are many materials whose dielectric properties are described by a stretched exponential, the so-called Kohlrausch-Williams-Watts (KWW) relaxation function. Its physical origin and statistical-mechanical foundation have been a matter of debate in the literature. In this Letter we suggest a model of dielectric relaxation, which naturally leads to a stretched exponential decay function. Some essential characteristics of the underlying charge conduction mechanisms are considered. A kinetic description of the relaxation and charge transport processes is proposed in terms of equations with time-fractional derivatives

  12. Multiple refraction switches realized by stretching elastomeric scatterers in sonic crystals

    Directory of Open Access Journals (Sweden)

    Y. Huang

    2015-02-01

    Full Text Available The effect of out-of-plane pre-stretch on the 2D sonic crystal with stretchable elastomeric scatterers is explored. The hyperelastic scatterers are characterized by a compressible neo-Hookean model. The Dirichlet-to-Neumann (DtN map is adopted to obtain the band structure and equi-frequency contours. We focus on the first passband and find that a variety of switching functionalities for refraction behaviors can be realized in selected frequencies under a specific pre-stretch range. These refraction switches enable an active control of wave propagation and are applicable in advanced technologies where switchable and multifunctional sonic crystals are required.

  13. Pyrenean hyper-extension : breaking, thinning, or stretching of the crust ? A view from the central north-Pyrenean zone

    Science.gov (United States)

    de Saint Blanquat, Michel; Bajolet, Flora; Boulvais, Philippe; Boutin, Alexandre; Clerc, Camille; Delacour, Adélie; Deschamp, Fabien; Ford, Mary; Fourcade, Serge; Gouache, Corentin; Grool, Arjan; Labaume, Pierre; Lagabrielle, Yves; Lahfid, Abdeltif; Lemirre, Baptiste; Monié, Patrick; de Parseval, Philippe; Poujol, Marc

    2017-04-01

    The geology of the North Pyrenean Zone in the central Pyrenees allows for the observation in the field of the entire section of the Pyrenean rift, from the mantle to the crust and the Mesozoic cover (pre, syn and post rift). The good knowledge we have of the pre-Alpine history of the Pyrenees allows us to properly constrain the Alpine geological evolution of the pre-Triassic rocks which record both Variscan and Alpine orogenic cycles. The mantle outcrop as kilometric to centimetric fragments of peridotite dispersed within a carbonate metamorphic breccia. The study of peridotite serpentinisation shows several events of low-temperature serpentinisation, in contact with seawater. In some locallities, we can observe a mixture of fragments of variously serpentinized peridotites. This suggests a tectonic context where fragments of peridotites from different structural levels were sampled more or less synchronously. The granulitic basement is characterized by a Variscan syndeformational HT event (300-280 Ma). So far we have not found any trace of a Cretaceous HT event (> 500°C). On the other hand, the basement is affected by a regional metasomatism that began during the Jurassic and became more spatially focused with time until it was restricted to the Pyrenean rift during the Aptien, Albian and Cenomanian. The talc-chlorite metasomatism (120-95 Ma) shows an evolution from a static toward a syn-deformation hydrothermal event, under a more or less normal geothermal gradient. Extensional deformation is recorded by the reworking of several inherited low-angle Variscan tectonic contacts, but also by dispersed high-angle extensional shear zones formed under greenshist conditions. The metamorphic Mesozoic cover of the basement massifs, which constitute the so-called Internal Metamorphic Zone, is an allochtonous unit made of lenses of Mesozoic rocks enclosed into the breccia, which locally contains peridotite and basement clasts. The Mesozoic metamorphic carbonates show a first

  14. Two-stage unified stretched-exponential model for time-dependence of threshold voltage shift under positive-bias-stresses in amorphous indium-gallium-zinc oxide thin-film transistors

    Science.gov (United States)

    Jeong, Chan-Yong; Kim, Hee-Joong; Hong, Sae-Young; Song, Sang-Hun; Kwon, Hyuck-In

    2017-08-01

    In this study, we show that the two-stage unified stretched-exponential model can more exactly describe the time-dependence of threshold voltage shift (ΔV TH) under long-term positive-bias-stresses compared to the traditional stretched-exponential model in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). ΔV TH is mainly dominated by electron trapping at short stress times, and the contribution of trap state generation becomes significant with an increase in the stress time. The two-stage unified stretched-exponential model can provide useful information not only for evaluating the long-term electrical stability and lifetime of the a-IGZO TFT but also for understanding the stress-induced degradation mechanism in a-IGZO TFTs.

  15. High-resolution spectroscopy and analysis of the ν1/ν3 stretching dyad of osmium tetroxide

    International Nuclear Information System (INIS)

    Louviot, M.; Boudon, V.; Manceron, L.; Roy, P.; Balcon, D.

    2012-01-01

    OsO 4 is a heavy tetrahedral molecule that may constitute a benchmark for quantum chemistry calculations. Its favorable spin statistics (due to the zero nuclear spin of oxygen atoms) is such that only A 1 and A 2 rovibrational levels are allowed, leading to a dense, but quite easily resolved spectrum. Most lines are single ones, instead of complex line clusters as in the case of other heavy spherical-tops like SF 6 , for instance. It is thus possible to fully assign and fit the spectrum and to obtain precise experimental effective molecular parameters. The strong ν 3 stretching fundamental has been studied a long time ago as an isolated band [McDowell RS, Radziemski LJ, Flicker H, Galbraith HW, Kennedy RC, Nereson NG, et al. Journal of Chemical Physics 1978;88:1513-21; Bobin B, Valentin A, Henry L. Journal of Molecular Spectroscopy 1987;122:229-41]. We reinvestigate here this region and perform new assignments and effective Hamiltonian parameter fits for the four main isotopologues ( 192 OsO 4 , 190 OsO 4 , 189 OsO 4 , 188 OsO 4 ), by considering the ν 1 /ν 3 stretching dyad. A new experimental spectrum has been recorded at room temperature, thanks to a Bruker IFS 125 HR interferometer and using a natural abundance OsO 4 sample. Assignments and analyses were performed thanks to the SPVIEW and XTDS softwares, respectively [Wenger Ch, Boudon V, Rotger M, Sanzharov M, Champion J-P. Journal of Molecular Spectroscopy 2008;251:102-13]. We provide precise effective Hamiltonian parameters, including band centers and Coriolis interaction parameters. We discuss isotopic shifts and estimate the band centers for the three minor isotopologues ( 187 OsO 4 , 186 OsO 4 , 184 OsO 4 ). The Q branches of the first two of them are clearly identified in the experimental spectrum.

  16. Stretching Capabilities: Children with Disabilities Playing TV and Computer Games

    Science.gov (United States)

    Wasterfors, David

    2011-01-01

    Intervention studies show that if children with disabilities play motion-controlled TV and computer games for training purposes their motivation increases and their training becomes more intensive, but why this happens has not been explained. This article addresses this question with the help of ethnographic material from a public project in…

  17. Stretch-activated cation channel from larval bullfrog skin

    DEFF Research Database (Denmark)

    Hillyard, Stanley D; Willumsen, Niels J; Marrero, Mario B

    2010-01-01

    Cell-attached patches from isolated epithelial cells from larval bullfrog skin revealed a cation channel that was activated by applying suction (-1 kPa to -4.5 kPa) to the pipette. Activation was characterized by an initial large current spike that rapidly attenuated to a stable value and showed ...

  18. Ellipticity of near-threshold harmonics from stretched molecules.

    Science.gov (United States)

    Li, Weiyan; Dong, Fulong; Yu, Shujuan; Wang, Shang; Yang, Shiping; Chen, Yanjun

    2015-11-30

    We study the ellipticity of near-threshold harmonics (NTH) from aligned molecules with large internuclear distances numerically and analytically. The calculated harmonic spectra show a broad plateau for NTH which is several orders of magnitude higher than that for high-order harmonics. In particular, the NTH plateau shows high ellipticity at small and intermediate orientation angles. Our analyses reveal that the main contributions to the NTH plateau come from the transition of the electron from continuum states to these two lowest bound states of the system, which are strongly coupled together by the laser field. Besides continuum states, higher excited states also play a role in the NTH plateau, resulting in a large phase difference between parallel and perpendicular harmonics and accordingly high ellipticity of the NTH plateau. The NTH plateau with high intensity and large ellipticity provides a promising manner for generating strong elliptically-polarized extreme-ultraviolet (EUV) pulses.

  19. Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios

    Science.gov (United States)

    Sekir, Ufuk; Arabaci, Ramiz; Akova, Bedrettin

    2015-01-01

    AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P hamstring muscle strength at both the 60°/s and 180°/s test speeds (P 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05). CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines. PMID:26495249

  20. The Electrical Conductivity of Stretched Polyaniline and Polypyrrole Coated Yarns

    Directory of Open Access Journals (Sweden)

    M. Nouri

    2009-12-01

    Full Text Available The nylon and nylon/lycra yarns were coated with electrically conductive polymers such as polyaniline and polypyrrole, via chemical polymerization process. Electrical conductivity of the coated yarns was measured at variousstrain levels using two-point probe technique and their strain sensitivities were studied. The results showed that, electrical conductivity of the coated yarns decreased with an increase in strain level. A sharp decrease in the electrical conductivity of the nylon/lycra coated yarn with the strain level was recorded whereas, a small drop in the electrical conductivity of the nylon coated yarn was observed. Linear relationships were found between the electrical conductivity and length for the nylon and nylon/lycra coated yarns. The polyaniline coated yarns showed higher strain sensitivity compared to polypyrrole coated yarns. Repeatability of the strain sensitivity of the coated yarns was examined and the coated nylon/lycra yarn showed better repeatability compared to that of coated nylon yarn. The coated yarns were proposed as a flexible strain sensor in the field of intelligent materials.